MJ Botany chap.3/Genetics and breeding of distinct cannabis by Robert Connell Clarke.

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Marijuana Botany
An Advanced Study: The Propagation and Breeding of Distinctive Cannabis
by Robert Connell Clarke

Chapter 3 - Genetics and Breeding of Cannabis

List of Favorable Traits of Cannabis in Which Variation Occurs

1. General Traits

a) Size and Yield
B) Vigor
c) Adaptability
d) Hardiness
e) Disease and Pest Resistance
f) Maturation
g) Root Production
h) Branching
i) Sex

2. Seedling Traits

3. Leaf Traits

4. Fiber Traits

Floral Traits


Calyx Size
Cannabinoid Level
Taste and Aroma
Persistence of Aromatic Principles and Cannabinoids
h) Trichome Type
i) Resin Quantity and Quality
j) Resin Tenacity
k) Drying and Curing Rate
I) Ease of Manicuring
m) Seed Characteristics
n) Maturation
o) Flowering
p) Ripening
q) Cannabinoid Profile

6. Gross Phenotypes of Cannabis Strains

General Traits
a) Size and Yield - The size of an individual Cannabis plant is determined by environmental factors such as room for root and shoot growth, adequate light and nutrients, and proper irrigation. These environmental factors influence the phenotypic image of genotype, but the genotype of the individual is responsible for overall variations in gross morphology, including size. Grown under the same conditions, particularly large and small individuals are easily spotted and selected. Many dwarf Cannabis plants have been reported and dwarfism may be subject to genetic control, as
it is in many higher plants, such as dwarf corn and citrus. Cannabis parents selected for large size tend to produce offspring of a larger average size each year. Hybrid crosses between tall (Cannabis sativa-Mexico) strains and short (Cannabis ruderalis-Russia) strains yield F1 offspring of intermediate height (Beutler and der Marderosian 1978). Hybrid vigor, however, will influence the size of offspring more than any other genetic factor. The increased size of hybrid offspring is often amazing and accounts for much of the success of Cannabis cultivators in raising large plants.
It is not known whether there is a set of genes for "gigantism" in Cannabis or whether polyploid individuals really yield more than diploid due to increased chromosome count. Tetraploids tend to be taller and their water requirements are often higher than diploids. Yield is determined by the overall production of fiber, seed, or resin and selective breeding can be used to increase the yield of any one of these products. However, several of these traits may be closely related, and it may be impossible to breed for one without the other (gene linkage). Inbreeding of a pure strain increases yield only if high yield parents are selected. High yield plants, staminate or pistillate, are not finally selected until the plants are dried and manicured. Because of this, many of the most vigorous plants are crossed and seeds selected after harvest when the yield can be measured.

B) Vigor - Large size is often also a sign of healthy vigorous growth. A plant that begins to grow immediately will usually reach a larger size and produce a higher yield in a short growing season than a sluggish, slow-growing plant. Parents are always selected for rich green foliage and rapid, responsive growth. This will ensure that genes for certain weaknesses in overall growth and development are bred out of the population while genes for strength and vigor remain.

c) Adaptability - It is important for a plant with a wide distribution such as Cannabis to be adaptable to many different environmental conditions. Indeed, Cannabis is one of the most genotypically diverse and phenotypically plastic plants on earth; as a result it has adapted to environmental conditions ranging from equatorial to temperate climates. Domestic agricultural circumstances also dictate that Cannabis must be grown under a great variety of conditions,

Plants to be selected for adaptability are cloned and grown in several locations. The parental stocks with the highest survival percentages can be selected as prospective parents for an adaptable strain. Adaptability is really just another term for hardiness under varying growth conditions.

d) Hardiness - The hardiness of a plant is its overall resistance to heat and frost, drought and overwatering, and so on. Plants with a particular resistance appear when adverse conditions lead to the death of the rest of a large population. The surviving few members of the population might carry inheritable resistance to the environmental factor that destroyed the majority of the population. Breeding these survivors, subjecting the offspring to continuing stress conditions, and selecting carefully for several generations should result in a pure-breeding strain with increased resistance to drought, frost, or excessive heat.

e) Disease and Pest Resistance - In much the same way as for hardiness a strain may be bred for resistance to a certain disease, such as damping-off fungus. If flats of seedlings are infected by damping-off disease and nearly all of them die, the remaining few will have some resistance to damping-off fungus. If this resistance is inheritable, it can be passed on to subsequent generations by crossing these surviving plants. Subsequent crossing, tested by inoculating flats of seedling offspring with damping-off fungus, should yield a more resistant strain.

Resistance to pest attack works in much the same way. It is common to find stands of Cannabis where one or a few plants are infested with insects while adjacent plants are untouched. Cannabinoid and terpenoid resins are most probably responsible for repelling insect attack, and levels
of these vary from plant to plant. Cannabis has evolved defenses against insect attack in the form of resin-secreting glandular trichomes, which cover the reproductive and associated vegetative structures of mature plants. Insects, finding the resin disagreeable, rarely attack mature Cannabis flowers. However, they may strip the outer leaves of the same plant because these develop fewer glandular trichomes and protective resins than the flowers. Nonglandular cannabinoids and other compounds produced within leaf and stem tissues which possibly inhibit insect attack, may account for the varying resistance of seedlings and vegetative juvenile plants to pest infestation. With the popularity of greenhouse Cannabis cultivation, a strain is
needed with increased resistance to mold, mite, aphid,- or white fly infestation. These problems are often so severe that greenhouse cultivators destroy any plants which are attacked. Molds usually reproduce by wind-borne spores, so negligence can rapidly lead to epidemic disaster. Selection and breeding of the least infected plants should result in strains with increased resistance.

f) Maturation - Control of the maturation of Cannabis is very important no matter what the reason for growing it. If Cannabis is to be grown for fiber it is important that the maximum fiber content of the crop be reached early and that all of the individuals in the crop mature at the same time to facilitate commercial harvesting. Seed production requires the even maturation of both pollen and seed parents to ensure even setting and maturation of seeds. An uneven maturation of seeds would mean that some seeds would drop and be lost while others are still ripening. An understanding of floral maturation is the key to the production of high quality drug Cannabis. Changes in gross morphology are accompanied by changes in cannabinoid and terpenoid production and serve as visual keys to deter-
mining the ripeness of Cannabis flowers.

A cannabis plant may mature either early or late, be fast or slow to flower, and ripen either evenly or sequentially.

Breeding for early or late maturation is certainly a reality; it is also possible to breed for fast or slow flowering and even or sequential ripening. In general, crosses between early-maturing plants give rise to early-maturing offspring, crosses between late-maturing plants give rise to late-maturing offspring, and crosses between late- and early-maturing plants give rise to offspring of intermediate maturation. This seems to indicate that maturation of Cannabis is not controlled by the simple dominance and recessiveness of one gene but probably results from incomplete dominance and a combination of genes for separate aspects of maturation. For instance, Sorghum maturation is controlled by four separate genes. The sum of these
genes produces a certain phenotype for maturation. Although breeders do not know the action of each specific gene, they still can breed for the total of these traits and achieve results more nearly approaching the goal of timely maturation than the parental strains.

g) Root Production - The size and shape of Cannabis root systems vary greatly. Although every embryo sends out a taproot from which lateral roots grow, the individual growth pattern and final size and shape of the roots vary considerably. Some plants send out a deep taproot, up to 1 meter (39 inches) long, which helps support the plant against winds and rain. Most Cannabis plants, however, produce a poor taproot which rarely extends more than 30 centimeters (1 foot). Lateral growth is responsible for most of the roots in Cannabis plants. These fine lateral roots offer the plant additional support but their primary function is to absorb water and nutrients from the soil. A large root system will be able to feed and support a large plant. Most lateral roots grow near the surface of the soil where there is more water, more oxygen, and more available nutrients. Breeding for root size and shape may prove beneficial for the production of large rain- and wind-resistant strains. Often Cannabis plants, even very large ones, have very small and sensitive root systems. Recently, certain alkaloids have been discovered in the roots of Cannabis that might have some medical value. If this proves the case, Cannabis may be cultivated and bred for high alkaloid levels in the roots to be used in the commercial production of pharmaceuticals.

As with many traits, it is difficult to make selections for root types until the parents are harvested. Because of this many crosses are made early and seeds selected later.

h) Branching - The branching pattern of a Cannabis plant is determined by the frequency of nodes along each branch and the extent of branching at each node. For examples, consider a tall, thin plant with slender limbs made up of long internodes and nodes with little branching (Oaxaca, Mexico strain). Compare this with a stout, densely branched plant with limbs of short internodes and highly branched nodes (Hindu Kush hashish strains). Different branching patterns are preferred for the different agricultural applications of fiber, flower, or resin production. Tall, thin plants with long internodes and no branching are best adapted to fiber production; a short, broad plant with short internodes and well developed branching is best adapted to floral production. Branching structure is selected that will tolerate heavy rains and high winds without breaking. This is quite advantageous to outdoor growers in temperate zones with short seasons. Some breeders select tall, limber plants (Mexico) which bend in the wind; others select short, stiff plants (Hindu Kush) which resist the weight of water without bending.

i) Sex - Attempts to breed offspring of only one sexual type have led to more misunderstanding than any other facet of Cannabis genetics. The discoveries of McPhee (1925) and Schaffner (1928) showed that pure sexual type and hermaphrodite conditions are inherited and that the percentage of sexual types could be altered by crossing with certain hermaphrodites. Since then it has generally been assumed by researchers and breeders that a cross between ANY unselected hermaphrodite plant and a pistillate seed-parent should result in a population of all pistillate offspring. This is not the case. In most cases, the offspring of hermaphrodite parents tend toward hermaphrodism, which is largely unfavorable for the production of Cannabis other than fiber hemp. This is not to say that there is no tendency for hermaphrodite crosses to alter sex ratios in the offspring. The accidental release of some pollen from predominantly pistillate hermaphrodites, along with the complete eradication of nearly every staminate and staminate hermaphrodite plant may have led to a shift in sexual ratio in domestic populations of sinsemilla drug Cannabis. It is commonly observed that these strains tend toward 60% to 80% pistillate plants and a few pistillate hermaphrodites are not uncommon in these populations.
However, a cross can be made which will produce nearly all pistillate or staminate individuals. If the proper pistillate hermaphrodite plant is selected as the pollen-parent and a pure pistillate plant is selected as the seed-parent it is possible to produce an F1, and subsequent generations, of nearly all pistillate offspring. The proper pistillate hermaphrodite pollen-parent is one which has grown as a pure pistillate plant and at the end of the season, or under artificial environmental stress, begins to develop a very few staminate flowers. If pollen from these few staminate flowers forming on a pistillate plant is applied to a pure pistillate seed parent, the resulting F1 generation should be almost all pistillate with only a few pistillate hermaphrodites. This will also be the case if the selected pistillate hermaphrodite pollen source is selfed and bears its own seeds. Remember that a selfed hermaphrodite gives rise to more hermaphrodites, but a selfed pistillate plant that has given rise to a limited number of staminate flowers in response to environmental stresses should give rise to nearly all pistillate offspring. The F1 offspring may have a slight tendency to produce a few staminate flowers under further environmental stress and these are used to produce F2 seed. A monoecious strain produces 95+% plants with many pistillate and staminate flowers, but a dioecious strain produces 95+% pure pistillate or staminate plants. A plant from a dioecious strain with a few inter-sexual flowers is a pistillate or staminate hermaphrodite. Therefore, the difference between monoecism and hermaphrodism is one of degree, determined by genetics and environment.

Crosses may also be performed to produce nearly all staminate offspring. This is accomplished by crossing a pure staminate plant with a staminate plant that has produced a few pistillate flowers due to environmental stress, or selfing the latter plant. It is readily apparent that in the wild this is not a likely possibility. Very few staminate plants live long enough to produce pistillate flowers, and when this does happen the number of seeds produced is limited to the few pistillate flowers that occur. In the case of a pistillate hermaphrodite, it may produce only a few staminate flowers, but each of these may produce thousands of pollen grains, any one of which may fertilize one of the plentiful pistillate flowers, producing a seed. This is
another reason that natural Cannabis populations tend toward predominantly pistillate and pistillate hermaphrodite plants. Artificial hermaphrodites can be produced by hormone sprays, mutilation, and altered light cycles. These should prove most useful for fixing traits and sexual type.

Drug strains are selected for strong dioecious tendencies. Some breeders select strains with a sex ratio more nearly approaching one than a strain with a high pistillate sex ratio. They believe this reduces the chances of pistillate plants turning hermaphrodite later in the season.

2. Seedling Traits

Seedling traits can be very useful in the efficient and purposeful selection of future parental stock. If accurate selection can be exercised on small seedlings, much larger populations can be grown for initial selection, as less space is required to raise small seedlings than mature plants. Whorled phyllotaxy and resistance to damping-off are two traits that may be selected just after emergence of the embryo from the soil. Early selection for vigor, hardiness, resistance, and general growth form may be made when the seedlings are from 30 to 90 centimeters (1 to 3 feet) tall. Leaf type, height, and branching are other criteria for early selection. These early-selected plants cannot be bred until they mature, but selection is the primary and most important step in plant improvement.
Whorled phyllotaxy is associated with subsequent anomalies in the growth cycle (i.e., multiple leaflets and flattened or clubbed stems). Also, most whorled plants are staminate and whorled phyllotaxy may be sex-linked.

3. Leaf Traits

Leaf traits vary greatly from strain to strain. In addition to these regularly occurring variations in leaves, there are a number of mutations and possible traits in leaf shape. It may turn out that leaf shape is correlated with other traits in Cannabis. Broad leaflets might be associated with a low calyx-to-leaf ratio and narrow leaflets might be associated with a high calyx-to-leaf ratio. If this is the case, early selection of seedlings by leaflet shape could determine the character of the flowering clusters at harvest. Both compound and webbed leaf variations seem to be hereditary, as are general leaf characteristics. A breeder may wish to develop a unique leaf shape for an ornamental strain or increase leaf yield for pulp production.

A peculiar leaf mutation was reported from an F1- Colombian plant in which two leaves on the plant, at the time of flowering, developed floral clusters of 5-10 pistillate calyxes at the intersection of the leaflet array and the petiole attachment, on the adaxial (top) side of the leaf. One of these clusters developed a partial staminate flower but fertilization was unsuccessful. It is unknown if this mutation is hereditary.

From Afghanistan, another example has been observed with several small floral clusters along the petioles of many of the large primary leaves.

4. Fiber Traits

More advanced breeding has occurred in fiber strains than any other type of Cannabis. Over the years many strains have been developed with improved maturation, increased fiber content, and improved fiber quality as regards length, strength, and suppleness. Extensive breeding programs have been carried on in France, Italy, Russia, and the United States to develop better varieties of fiber Cannabis. Tall limbless strains that are monoecious are most desirable. Monoeciousness is favored, because in dioecious populations the staminate plants will mature first and the fibers will become brittle before the pistillate plants are ready for harvest. The fiber strains of Europe are divided into northern and southern varieties. The latter require higher temperatures and a longer vegetative period and as a result grow taller and yield more fiber.

5. Floral Traits

Many individual traits determine the floral characteristics of Cannabis This section will focus on the individual traits of pistillate floral clusters with occasional comments about similar traits in staminate floral clusters. Pistillate flowering clusters are the seed-producing organs of Cannabis; they remain on the plant and go through many changes that cannot be compared to staminate plants.

a) Shape - The basic shape of a floral cluster is determined by the internode lengths along the main floral axis and within individual floral clusters. Dense, long clusters result when internodes are short along a long floral axis and there are short internodes within the individual compact floral clusters (Hindu Kush). Airy clusters result when a plant forms a stretched floral axis with long internodes between well-branched individual floral clusters (Thailand).

The shape of a floral cluster is also determined by the general growth habit of the plant. Among domestic Cannabis phenotypes, for instance, it is obvious that floral clusters from a creeper phenotype plant will curve upwards at the end, and floral clusters from the huge upright phenotype will have long, straight floral clusters of various shapes. Early in the winter, many strains begin to stretch and cease calyx production in preparation for rejuvenation and subsequent vegetative growth in the spring. Staminate plants also exhibit variation in floral clusters. Some plants have tight clusters of staminate calyxes resembling inverted grapes (Hindu Kush) and others have long, hanging groups of flowers on long, exposed, leafless branches (Thailand).

B) Form - The form of a floral cluster is determined by the numbers and relative proportions of calyxes and flowers. A leafy floral cluster might be 70% leaves and have a calyx-to-leaf ratio of 1-to-4. It is obvious that strains with a high calyx-to-leaf ratio are more adapted to calyx production, and therefore, to resin production. This factor could be advantageous in characterizing plants as future parents of drug strains. At this point it must be noted that pistillate floral clusters are made up of a number of distinct parts. They include stems, occasional seeds, calyxes, inner leaves subtending calyx pairs (small, resinous, 1-3 leaflets), and outer leaves subtending entire floral clusters (larger, little resin, 3-11 leaflets). The ratios (by dry weight)
of these various portions vary by strain, degree of pollination, and maturity of the floral clusters. Maturation is a reaction to environmental change, and the degree of maturity reached is subject to climatic limits as well as breeder's preference. Because of this interplay between environment and genetics in the control of floral form it is often difficult to breed Cannabis for floral characteristics. A thorough knowledge of the way a strain matures is important in separating possible inherited traits of floral clusters from acquired traits. Chapter IV, Maturation and Harvesting of Cannabis, delves into the secrets and theories of maturation. For now, we will assume that the following traits are described from fully mature floral clusters (peak floral
stage) before any decline.

c) Calyx Size - Mature calyxes range in size from 2 to 12 millimeters (1/16 to 3/8 inch) in length. Calyx size is largely dependent upon age and maturity. Calyx size of a floral cluster is best expressed as the average length of the mature viable calyxes. Calyxes are still considered viable if both pistils appear fresh and have not begun to curl or change colors. At this time, the calyx is relatively straight and has not begun to swell with resin and change shape as it will when the pistils die. It is generally agreed that the production of large calyxes is often as important in determining the psychoactivity of a strain as the quantity of calyxes produced. Hindu Kush, Thai, and Mexican strains are some of the most psychoactive strains, and they are often characterized by large calyxes and seeds.

Calyx size appears to be an inherited trait in Cannabis. Completely acclimatized hybrid strains usually have many rather small calyxes, while imported strains with large calyxes retain that size when inbred.

Initial selection of large seeds increases the chance that offspring will be of the large-calyx variety. Aberrant calyx development occasionally results in double or fused calyxes, both of which may set seed. This phenomenon is most pronounced in strains from Thailand and India.

d) Color - The perception and interpretation of color in Cannabis floral clusters is heavily influenced by the imagination of the cultivator or breeder. A gold strain does not appear metallic any more than a red strain resembles a fire engine. Cannabis floral clusters are basically green, but
changes may take place later in the season which alter the color to include various shades. The intense green of chlorophyll usually masks the color of accessory pigments, Chlorophyll tends to break down late in the season and anthocyanin pigments also contained in the tissues are unmasked and allowed to show through. Purple, resulting from anthocyanin accumulation, is the most common color in living Cannabis, other than green. This color modification is usually triggered by seasonal change, much as the leaves of many deciduous trees change color in the fall. This does not mean, however, that expression of color is controlled by environment alone and is not an inheritable trait. For purple color to develop upon maturation, a strain must have the genetically controlled metabolic potential to produce anthocyanin pigments coupled with a responsiveness to environmental change such that anthocyanin pigments are unmasked and become visible. This also means that a strain could have the genes for expression of purple color but the color might never be expressed if the environmental conditions did not trigger anthocyanin pigmentation or chlorophyll breakdown. Colombian and Hindu Kush strains often develop purple coloration year after year when subjected to low night temperatures during maturation. Color changes will be discussed in more detail in Chapter IV- Maturation and Harvesting of Cannabis.

Carotenoid pigments are largely responsible for the yellow, orange, red, and brown colors of Cannabis. They also begin to show in the leaves and calyxes of certain strains as the masking green chlorophyll color fades upon maturation. Gold strains are those which tend to reveal underlying yellow and orange pigments as they mature. Red strains are usually closer to reddish brown in color, although certain carotenoid and anthocyanin pigments are nearly red and localized streaks of these colors occasionally appear in the petioles of very old floral clusters. Red color in pressed, imported tops is often a result of masses of reddish brown dried pistils.

Several different portions of floral cluster anatomy may change colors, and it is possible that different genes may control the coloring of these various parts.

The petioles, adaxial (top) surfaces, and abaxial (bottom) surfaces of leaves, as well as the stems, calyxes, and pistils color differently in various strains. Since most of the outer leaves are removed during manicuring, the color expressed by the calyxes and inner leaves during the late flowering stages will be all that remains in the final product. This is why strains are only considered to be truly purple or gold if the calyxes maintain those colors when dried. Anthocyanin accumulation in the stems is sometimes considered a sign of phosphorus deficiency but in most situations results from unharmful excesses of phosphorus or it is a genetic trait. Also, cold temperatures might interfere with phosphorus uptake resulting in a deficiency. Pis-
tils in Hindu Kush strains are quite often magenta or pink in color when they first appear. They are viable at this time and turn reddish brown when they wither, as in most strains. Purple coloration usually indicates that pistillate plants are over-mature and cannabinoid biosynthesis is
slowing down during cold autumn weather.

e) Cannabinoid Level - Breeding Cannabis for cannabinoid level has been accomplished by both licensed legitimate and clandestine researchers. Warmke (1942) and Warmke and Davidson (1943-44) showed that they could significantly raise or lower the cannabinoid level by selective breeding. Small (1975a) has divided genus Cannabis into four distinct chemotypes based on the relative amounts of THC and CBD. Recent research has shown that crosses between high THC: low CBD strains and low THC: high CBD strains yield offspring of cannabinoid content intermediate between the two parents. Beutler and der Marderosian (1978) analyzed the F1 offspring of the controlled cross C. Sativa (Mexico-high THC) X C. ruderalis (Russia-low THC) and found that they fell into two groups intermediate between the parents in THC level. This indicates that THC production is most likely controlled by more than one gene. Also the F1 hybrids of lower THC (resembling the staminate parent) were twice as frequent as the higher THC hybrids (resembling the pistillate parent). More research is needed to learn if THC production in Cannabis is associated with the sexual type of the high THC parent or if high THC characteristics are recessive. According to Small (1979) the cannabinoid ratios of strains grown in northern climates are a reflection of the cannabinoid ratio of the pure, imported, parental strain. This indicates that cannabinoid phenotype is genetically controlled, and the levels of the total cannabinoids are determined by environment. Complex highs produced by various strains of drug Cannabis may be blended by careful breeding to produce hybrids of varying psychoactivity, but the level of total psychoactivity is dependent on environment. This is also the telltale indication that unconscious breeding with undesirable low-THC parents could rapidly lead to the degeneration rather than improvement of a drug strain. It is obvious that individuals of fiber strains are of little if any use in breeding drug strains.

Breeding for cannabinoid content and the eventual characterization of varying highs produced by Cannabis is totally subjective guesswork without the aid of modern analysis techniques. A chromatographic analysis system would allow the selection of specific cannabinoid types, especially staminate pollen parents. Selection of staminate parents always presents a problem when breeding for cannabinoid content. Staminate plants usually express the same ratios of cannabinoids as their pistiliate counterparts but in much lower quantities, and they are rarely allowed to reach full maturity for fear of seeding the pistillate portion of the crop. A simple bioassay for THC content of staminate plants is performed by leaving a series of from three to five numbered bags of leaves and tops of various prospective pollen parents along with some rolling papers in several locations frequented by a steady repeating crowd of marijuana smokers. The bag completely consumed first can be considered the most desirable to smoke and possibly
the most psychoactive. It would be impossible for one person to objectively select the most psychoactive staminate plant since variation in the cannabinoid profile is subtle. The bioassay reported here is in effect an unstructured panel evaluation which averages the opinions of unbiased testers who are exposed to only a few choices at a time. Such bioassay results can enter into selecting the staminate parent.

It is difficult to say how many genes might control THC-acid synthesis. Genetic control of the biosynthetic pathway could occur at many points through the action of enzymes controlling each individual reaction. It is generally accepted that drug strains have an enzyme system which quickly converts CBD-acid to THC-acid, favoring THC-acid accumulation. Fiber strains lack this enzyme activity, so CBD-acid accumulalion is favored since there is little conversion to THC-acid. These same enzyme systems are probably also sensitive to changes in heat and light.

It is supposed that variations in the type of high associated with different strains of Cannabis result from varying levels of cannabinoids. THC is the primary psychoactive ingredient which is acted upon synergistically by small amounts of CBN, CBD, and other accessory cannabinoids. Terpenes and other aromatic constituents of Cannabis might also potentiate or suppress the effect of THC. We know that cannabinoid levels may be used to establish cannabinoid phenotypes and that these phenotypes are passed on from parent to offspring. Therefore, cannabinoid levels are in part determined by genes. To accurately characterize highs from various individuals and establish criteria for breeding strains with particular cannabinoid
contents, an accurate and easy method is needed for measuring cannabinoid levels in prospective parents. Inheritance and expression of cannabinoid chemotype is certainly complex.

f) Taste and Aroma - Taste and aroma are closely linked. As our senses for differentiating taste and aroma are connected, so are the sources of taste and aroma in Cannabis. Aroma is produced primarily by aromatic terpenes produced as components of the resin secreted by glandular trichomes on the surface of the calyxes and subtending leaflets. When a floral cluster is squeezed, the resinous heads of glandular trichomes rupture and the aromatic terpenes are exposed to the air. There is often a large difference between the aroma of fresh and dry floral clusters. This is explained by the polymerization (joining together in a chain) of many of the smaller molecules of aromatic terpenes to form different aromatic and nonaromatic terpene polymers. This happens as Cannabis resins age and mature, both while the plant is growing and while curing after harvest. Additional aromas may interfere with the primary terpenoid components, such as ammonia gas and other gaseous products given off by the curing, fermentation or spoilage of the tissue (non-resin) portion of the floral clusters.

A combination of at least twenty aromatic terpenes (103 are known to occur in Cannabis) and other aromatic compounds control the aroma of each plant. The production of each aromatic compound may be influenced by many genes; therefore, it is a complex matter to breed Cannabis for aroma. Breeders of perfume roses often are amazed at the complexity of the genetic control of aroma, Each strain, however, has several characteristic aromas, and these are occasionally transmitted to hybrid offspring such that they resemble one or both parents in aroma. Many
times breeders complain that their strain has lost the desired aromatic characteristics of the parental strains. Fixed hybrid strains will develop a characteristic aroma that is hereditary and often true-breeding. The cultivator with preservation of a particular aroma as a goal can clone the individual with a desired aroma in addition to breeding it. This is good insurance in case the aroma is lost in the offspring by segregation and recombination of genes.

The aromas of fresh or dried clusters are sampled and compared in such a way that they are separated to avoid confusion. Each sample is placed in the corner of a twice-folded, labeled piece of unscented writing paper at room temperature (above 650). A light squeeze will release the aromatic principles contained within the resin exuded by the ruptured glandular trichome head. When sampling, never squeeze a floral cluster directly, as the resins will adhere to the fingers and bias further sampling. The folded paper conveniently holds the floral cluster, avoids confusion during sampling, and contains the aromas as a glass does in wine tasting.

Taste is easily sampled by loosely rolling dried floral clusters in a cigarette paper and inhaling to draw a taste across the tongue. Samples should be approximately the same size.

Taste in Cannabis is divided into three categories according to usage: the taste of the aromatic components carried by air that passes over the Cannabis when it is inhaled without being lighted; the taste of the smoke from burning Cannabis; and the taste of Cannabis when it is consumed orally. These three are separate entities.

The terpenes contained in a taste of unlighted Cannabis are the same as those sensed in the aroma, but perceived through the sense of taste instead of smell. Orally ingested Cannabis generally tastes bitter due to the vegetative plant tissues, but the resin is characteristically spicy and hot,
somewhat like cinnamon or pepper. The taste of Cannabis smoke is determined by the burning tissues and vaporizing terpenes. These terpenes may not be detected in the aroma and unlighted taste.

Biosynthetic relationships between terpenes and cannabinoids have been firmly established. Indeed, cannabinoids are synthesized within the plant from terpene precursors. It is suspected that changes in aromatic terpene levels parallel changes in cannabinoid levels during maturation. As connections between aroma and psychoactivity are uncovered, the breeder will be better able to make field selections of prospective high-THC parents without complicated analysis.

g) Persistence of Aromatic Principles and Cannabinoids - Cannabis resins deteriorate as they age, and the aromatic principles and cannabinoids break down slowly until they are hardly noticeable. Since fresh Cannabis is only available once a year in temperate regions, an important breeding goal has been a strain that keeps well when packaged. Packageability and shelf life are important considerations in the breeding of fresh fruit species and will prove equally important if trade in Cannabis develops after legalization.

h) Trichome Type - Several types of trichomes are present on the epidermal surfaces of Cannabis. Several of these trichomes are glandular and secretory in nature and are divided into bulbous, capitate sessile, and capitate stalked types. Of these, the capitate stalked glandular trichomes are apparently responsible for the intense secretion of Cannabinoid laden resins. Plants with a high density of capitate stalked trichomes are a logical goal for breeders of drug Cannabis. The number and type of trichomes is easily characterized by observation with a small hand lens (10X to 50X). Recent research by V. P. Soroka (1979) concludes that a positive correlation exists between the number of glandular trichomes on leaves and calyxes and the various cannabinoid contents of the floral clusters. In other words, many capitate stalked trichomes means higher THC levels.

i) Resin Quantity and Quality - Resin production by the glandular trichomes varies. A strain may have many glandular trichomes but they may not secrete very much resin. Resin color also varies from strain to strain. Resin heads may darken and become more opaque as they mature, as suggested by several authors. Some strains, however, produce fresh resins that are transparent amber instead of clear and colorless, and these are often some of the most psychoactive strains. Transparent resins, regardless of color, are a sign that the plant is actively carrying out resin biosynthesis. When biosynthesis ceases, resins turn opaque as cannabinoid and aromatic levels decline. Resin color is certainly an indication of the conditions inside the resin head, and this may prove to be another important criterion for breeding.

j) Resin Tenacity - For years strains have been bred for hashish production. Hashish is formed from detached resin heads. In modern times it might be feasible to breed a strain with high resin production that gives up its precious covering of resin heads with only moderate shaking, rather than the customary flailing that also breaks up the plant. This would facilitate hashish production. Strains that are bred for use as marijuana would benefit from extremely tenacious resin heads that would not fall off during packaging and shipment.

k) Drying and Curing Rate - The rate and extent to which Cannabis dries is generally determined by the way it is dried, but, all conditions being the same, some strains dry much more rapidly and completely than others. It is assumed that resin has a role in preventing desiccation and high resin content might retard drying. However, it is a misconception that resin is secreted to coat and seal the surface of the calyxes and leaves. Resin is secreted by glandular trichomes, but they are trapped under a cuticle layer surrounding the head cells of the trichome holding the resin away from the surface of the leaves. There it would rarely if ever have a chance to seal the surface of the epidermal layer and prevent the transpiration of water. It seems that an alternate reason must be found for the great variations in rate and extent of drying. Strains may be bred that dry and cure rapidly to save valuable time.

1) Ease of Manicuring - One of the most time-consuming aspects of commercial drug Cannabis production is the seemingly endless chore of manicuring, or removing the larger leaves from the floral clusters. These larger outer leaves are not nearly as psychoactive as the inner leaves and calyxes, so they are usually removed before selling as marijuana. Strains with fewer leaves obviously require less time to manicure. Long petioles on the leaves facilitate removal by hand with a small pair of scissors. If there is a marked size difference between very large outer leaves and tiny, resinous inner leaves it is easier to manicure quickly because it is easier to see which leaves to remove.

m) Seed Characteristics - Seeds may be bred for many characteristics including size, oil content, and protein content. Cannabis seed is a valuable source of drying oils, and Cannabis-seed cake is a fine feed for ranch animals. Higher-protein varieties may be developed for food. Also, seeds are selected for rapid germination rate.

n) Maturation - Cannabis strains differ greatly as to when they mature and how they respond to changing environment. Some strains, such as Mexican and Hindu Kush, are famous for early maturation, and others, such as Colombian and Thai, are stubborn in maturing and nearly always
finish late, if at all. Imported strains are usually characterized as either early, average, or late in maturing; however, a particular strain may produce some individuals which mature early and others which mature late. Through selection, breeders have, on the one hand, developed strains that mature in four weeks, outdoors under temperate conditions; and on the other hand, they have developed greenhouse strains that mature in up to four months in their protected environment. Early maturation is extremely advantageous to growers who live in areas of late spring and early fall freezes. Consequently, especially early-maturing plants are selected as parents for future early-maturing strains.

o) Flowering - Once a plant matures and begins to bear flowers it may reach peak floral production in a few weeks, or the floral clusters may continue to grow and develop for several months. The rate at which a strain flowers is independent of the rate at which it matures, so a plant may
wait until late in the season to flower and then grow extensive, mature floral clusters in only a few weeks.

p) Ripening - Ripening of Cannabis flowers is the final step in their maturation process Floral clusters will usually mature and ripen in rapid succession, but sometimes large floral clusters will form and only after a period of apparent hesitation will the flowers begin to produce resin and ripen. Once ripening starts it usually spreads over the entire plant, but some strains, such as those from Thailand, are known to ripen a few floral clusters at a time over several months. Some fruit trees are similarly everbearing with a yearlong season of production. Possibly Cannabis strains could be bred that are true everbearing perennials that continue to flower and mature consistently all year long.

q) Cannabinoid Profile - It is supposed that variations in the type of high associated with different strains of Cannabis result from varying levels of cannabinoids. THC is the primary psychoactive ingredient which is acted upon synergistically by small amounts of CBN, CBD, and other accessory cannabinoids. We know that cannabinoid levels may be used to establish cannabinoid phenotypes and that these phenotypes are passed on from parent to offspring. Therefore, cannabinoid levels are in part determined by genes. To accurately characterize highs from various individuals and establish criteria for breeding strains with particular cannabinoid contents, an accurate and easy method is necessary for measuring cannabinoid levels in prospective parents.

Various combinations of these traits are possible and inevitable. The traits that we most often see are most likely dominant and any effort to alter genetics and improve Cannabis strains are most easily accomplished by concentrating on the major phenotypes for the most important traits. The
best breeders set high goals of a limited scope and adhere to their ideals.

6. Gross Phenotypes of Cannabis Strains

The gross phenotype or general growth form is determined by size, root production, branching pattern, sex, maturation, and floral characteristics. Most imported varieties have characteristic gross phenotypes although there tend to be occasional rare examples of almost every phenotype in nearly every variety. This indicates the complexity of genetic control determining gross phenotype. Hybrid crosses between imported pure varieties were the beginning of nearly every domestic strain of Cannabis. In hybrid crosses, some dominant characteristics from each parental
variety are exhibited in various combinations by the F1 offspring. Nearly all of the offspring will resemble both parents and very few will resemble only one parent. This sounds like it is saying a lot, but this F1 hybrid generation is far from true-breeding and the subsequent F2 generation will exhibit great variation, tending to look more like one or the other of the original imported parental varieties, and will also exhibit recessive traits not apparent in either of the original parents. If the F1 offspring are desirable plants it will be difficult to continue the hybrid traits in subsequent generations. Enough of the original F1 hybrid seeds are produced so they may be used year after year to produce uniform crops of desirable plants.

Phenotypes and Characteristics of Imported Strains

Following is a list of gross phenotypes and characteristics for many imported strains of Cannabis.

1. Fiber Strain Gross Phenotypes (hemp types)

2. Drug Strain Gross Phenotypes

a) Colombia - highland, lowland (marijuana)
B) Congo - (marijuana)
c) Hindu Kush - Afghanistan and Pakistan (hashish)
d) Southern India - (ganja marijuana)
e) Jamaica - Carribean hybrids
f) Kenya - Kisumu (dagga marijuana)
g) Lebanon - (hashish)
h) Malawi, Africa - Lake Nyasa (dagga marijuana)
i) Mexico - Michoacan, Oaxaca, Guerrero (marijuana)
j) Morocco - Rif mountains (kif marijuana and hashish)
k) Nepal - wild (ganja marijuana and hashish)
l) Russian - ruderalis (uncultivated)
m) South Africa - (dagga marijuana)
n) Southeast Asia - Cambodia, Laos, Thailand, Vietnam (ganja marijuana)

3. Hybrid Drug Phenotypes

a) Creeper Phenotype
B) Huge Upright Phenotype

In general the F1 and F2 pure-bred offspring of these imported varieties are more similar to each other than they are to other varieties and they are termed pure strains. However, it should be remembered that these are average gross phenotypes and recessive variations within each trait
will occur. In addition, these representations are based on unpruned plants growing in ideal conditions and stress will alter the gross phenotype. Also, the protective environment of a greenhouse tends to obscure the difference between different strains. This section presents information that is
used in the selection of pure strains for breeding.

1. Fiber Strain Gross Phenotypes

Fiber strains are characterized as tall, rapidly maturing, limbless plants which are often monoecious. This growth habit has been selected by generations of fiber-producing farmers to facilitate forming long fibers through even growth and maturation. Monoecious strains mature more evenly than dioecious strains, and fiber crops are usually not grown long enough to set seed which interferes with fiber production. Most varieties of fiber Cannabis originate in the northern temperate climates of Europe, Japan, China and North America. Several strains have been selected from the prime hemp growing areas and offered commercially over the last fifty years in both Europe and America. Escaped fiber strains of the midwestern United
States are usually tall, skinny, relatively poorly branched, weakly flowered, and low in cannabinoid production. They represent an escaped race of Cannabis sativa hemp. Most fiber strains contain CBD as the primary cannabinoid and little if any THC.

2. Drug Strain Gross Phenotypes

Drug strains are characterized by Delta1-THC as the primary cannabinoid, with low levels of other accessory cannabinoids such as THCV, CBD, CBC, and CBN. This results from selective breeding for high potency or natural selection in niches where Delta1-THC biosynthesis favors survival.

a) Colombia - (0 to 10 north latitude)

Colombian Cannabis originally could be divided into two basic strains: one from the low-altitude humid coastal areas along the Atlantic near Panama, and the other from the more arid mountain areas inland from Santa Marta. More recently, new areas of cultivation in the interior plateau of southern central Colombia and the highland valleys stretching southward from the Atlantic coast have become the primary areas of commercial export Cannabis cultivation. Until recent years high quality Cannabis was available through the black market from both coastal and highland Colombia. Cannabis was introduced to Colombia just over 100 years ago, and its cultivation is deeply rooted in tradition. Cultivation techniques often involve transplanting of selected seedlings and other individual attention. The production of "la mona amarilla" or gold buds is achieved by girdling or removing a strip of bark from the main stem of a nearly mature plant, thereby restricting the flow of water, nutrients, and plant products. Over several days the leaves dry up and fall off as the flowers slowly die and turn yellow. This produces the highly prized "Colombian gold" so prevalent in the early to middle 1970s (Partridge 1973). Trade names such as "punta roja" (red tips [pistils] ), "Cali Hills," "choco," "lowland," "Santa Marta gold," and "purple" give us some idea of the color of older varieties and the location of cultivation.

In response to an incredible demand by America for Cannabis, and the fairly effective control of Mexican Cannabis importation and cultivation through tightening border security and the use of Paraquat, Colombian farmers have geared up their operations. Most of the marijuana smoked in America is imported from Colombia. This also means that the largest number of seeds available for domestic cultivation also originate in Colombia. Cannabis agri-business has squeezed out all but a few small areas where labor-intensive cultivation of high quality drug Cannabis such as "Ia mona amarilla" can continue. The fine marijuana of Colombia was often seedless, but commercial grades are nearly always well seeded. As a rule today, the more remote highland areas are the centers of commercial agriculture and few of the small farmers remain. It is thought that some highland farmers must still grow fine Cannabis, and occasional connoisseur crops surface. The older seeds from the legendary Colombian strains are now highly prized by breeders. In the heyday of "Colombian gold" this fine cerebral marijuana was grown high in the mountains. Humid lowland marijuana was characterized by stringy, brown, fibrous floral clusters of sedative narcotic high. Now highland marijuana has become the commercial product and is characterized by leafy brown floral clusters and sedative effect. Many of the unfavorable characteristics of imported Colombian Cannabis result from hurried commercial agricultural techniques combined with poor curing and storage. Colombian seeds still contain genes favoring vigorous growth and high THC production. Colombian strains also contain high levels of CBD and CBN, which could account for sedative highs and result from poor curmg and storage techniques. Domestic Colombian strains usually lack CBD and CBN. The commercial Cannabis market has brought about the eradication of some local strains by hybridizing with commercial strains.

Colombian strains appear as relatively highly branched conical plants with a long upright central stem, horizontal limbs and relatively short internodes. The leaves are characterized by highly serrated slender leaflets (7-11) in a nearly complete to overlapping circular array of varying shades of medium green. Colombian strains usually flower late in temperate regions of the northern hemisphere and may fail to mature flowers in colder climates. These strains favor the long equatorial growing seasons and often seem insensitive to the rapidly decreasing daylength during autumn in temperate latitudes. Because of the horizontal branching pattern of Colombian strains and their long growth cycle, pistillate plants tend to produce many flowering clusters along the entire length of the stem back to the central stalk. The small flowers tend to produce small, round, dark, mottled, and brown seeds. Imported and domestic Colombian Cannabis often tend to be more sedative in psychoactivity than other strains. This may be caused by the synergistic effect of THC with higher levels of CBD or CBN. Poor curing techniques on the part of Colombian farmers, such as sun drying in huge piles resembling compost heaps, may form CBN as a degradation product of THC. Colombian strains tend to make excellent hybrids
with more rapidly maturing strains such as those from Central and North America.

B) Congo - (5 north to 5 south latitude)

Most seeds are collected from shipments of commercial grade seeded floral clusters appearing in Europe.

c) Hindu Kush Range - Cannabis indica (Afghanistan and Pakistan) - (30 to 37 north latitude)

This strain from the foothills (up to 3,200 meters [10,000 feet) of the Hindu Kush range is grown in small rural gardens, as it has been for hundreds of years, and is used primarily for the production of hashish. In these areas hashish is usually made from the resins covering the pistillate calyxes and associated leaflets. These resins are removed by shaking and crushing the flowering tops over a silk screen and collecting the dusty resins that fall off the plants. Adulteration and pressing usually follow in the production of commercial hashish. Strains from this area are often used as type examples for Cannabis indica. Early maturation and the belief by clandestine cultivators that this strain may be exempt from laws controlling Cannabis sativa and indeed may be legal, has resulted in its proliferation throughout domestic populations of "drug" Cannabis. Names such as "hash plant" and "skunk weed" typify its acrid aroma reminiscent of "primo" hashish from the high valleys near Mazar-i-Sharif, Chitral, and Kandahar in Afghanistan and Pakistan.

This strain is characterized by short, broad plants with thick, brittle woody stems and short internodes. The main stalk is usually only four to six feet tall, but the relatively unbranched primary limbs usually grow in an upright fashion until they are nearly as tall as the central stalk and form a sort of upside-down conical shape. These strains are of medium size, with dark green leaves having 5 to 9 very wide, coarsely serrated leaflets in a circular array. The lower leaf surface is often lighter in color than the upper surface. These leaves have so few broad coarse leaflets that they are often compared to a maple leaf. Floral clusters are dense and appear along the entire length of the primary limbs as very resinous leafy balls. Most plants produce flowering clusters with a low calyx-to-leaf ratio, but the inner leaves associated with the calyxes are usually liberally encrusted with resin. Early maturation and extreme resin production is characteristic of these strains. This may be the result of acclimatization to northern temperate latitudes and selection for hashish production. The acrid smell associated with strains from the Hindu Kush appears very early in the seedling stage of both staminate and pistillate individuals and continues throughout the life of the plant. Sweet aromas do often develop but this strain usually loses
the sweet fragrance early, along with the clear, cerebral psychoactivity.

Short stature, early maturation, and high resin production make Hindu Kush strains very desirable for hybridizing and indeed they have met with great popularity. The gene pool of imported Hindu Kush strains seems to be dominant for these desirable characteristics and they seem readily passed on to the F1 hybrid generation. A fine hybrid may result from crossing a Hindu Kush variety with a late-maturing, tall, sweet strain from Thailand, India, or Nepal. This produces hybrid offspring of short stature, high resin content, early maturation, and sweet taste that will mature high quality flowers in northern climates. Many hybrid crosses of this type are made each year and are currently cultivated in many areas of North America. Hindu Kush seeds are usually large, round, and dark grey or black in coloring with some mottling.

d) India Centra1 Southern - Kerala, Mysore, and Madras regions (10 to 20 north latitude)

Ganja (or flowering Cannabis tops) has been grown in India for hundreds of years. These strains are usually grown in a seedless fashion and are cured, dried, and smoked as marijuana instead of being converted to hashish as in many Central Asian areas. This makes them of considerable inter-
est to domestic Cannabis cultivators wishing to reap the benefits of years of selective breeding for fine ganja by Indian farmers. Many Europeans and Americans now live in these areas of India and ganja strains are finding their way into domestic American Cannabis crops.

Ganja strains are often tall and broad with a central stalk up to 12 feet tall and spreading highly-branched limbs. The leaves are medium green and made up of 7 to 11 leaflets of moderate size and serration arranged in a circular array. The frond-like limbs of ganja strains result from extensive compound branching so that by the time floral clusters form they grow from tertiary or quaternary limbs. This promotes a high yield of floral clusters which in ganja strains tend to be small, slender, and curved. Seeds are usually small and dark. Many spicy aromas and tastes occur in Indian ganja strains and they are extremely resinous and psychoactive. Medicinal Cannabis of the late 1800s and early 1900s was usually Indian ganja.

e) Jamaica - (18 north latitude)

Jamaican strains were not uncommon in the late 1960s and early 1970s but they are much rarer today. Both green and brown varieties are grown in Jamaica. The top-of-the-line seedless smoke is known as the "lamb's bread" and is rarely seen outside Jamaica. Most purported Jamaican strains appear stringy and brown much like lowland or commercial Colombian strains. Jamaica's close proximity to Colombia and its position along the routes of marijuana smuggling from Colombia to Florida make it likely that Colombian varieties now predominate in Jamaica even if these varieties were not responsible for the original Jamaican strains. Jamaican strains resemble Colombian strains in leaf shape, seed type and general morphology but they tend to be a little taller, thinner, and lighter green. Jamaican strains produce a psychoactive effect of a particularly clear and cerebral nature, unlike many Colombian strains. Some strains may also have come to Jamaica from the Caribbean coast of Mexico, and this may account for the introduction of cerebral green strains.

f) Kenya - Kisumu (5 north to 5 south latitude)

Strains from this area have thin leaves and vary in color from light to dark green. They are characterized by cerebral psychoactivity and sweet taste. Hermaphrodites are common.

g) Lebanon - (34 north latitude)

Lebanese strains are rare in domestic Cannabis crops but do appear from time to time. They are relatively short and slender with thick stems, poorly developed limbs, and wide, medium-green leaves with 5 to 11 slightly broad leaflets. They are often early-maturing and seem to be quite leafy, reflecting a low calyx-to-leaf ratio. The calyxes are relatively large and the seeds flattened, ovoid and dark brown in color. As with Hindu Kush strains, these plants are grown for the production of screened and pressed hashish, and the calyx-to-leaf ratio may be less important than the total resin production for hashish making. Lebanese strains resemble Hindu Kush varieties in many ways and it is likely that they are related.

h) Malawi, Africa - (10 to 15 south latitude)

Malawi is a small country in eastern central Africa bordering Lake Nyasa. Over the past few years Cannabis from Malawi has appeared wrapped in bark and rolled tightly, approximately four ounces at a time. The nearly seedless flowers are spicy in taste and powerfully psychoactive. Enthusiastic American and European Cannabis cultivators immediately planted the new strain and it has become incorporated into several domestic hybrid strains. They appear as a dark green, large plant of medium height and strong limb growth. The leaves are dark green with coarsely serrated, large, slender leaflets arranged in a narrow, drooping, hand-like array. The leaves usually lack serrations on the distal (tip portion) 20% of each leaflet. The mature floral clusters are sometimes airy, resulting from long internodes, and are made up of large calyxes and relatively few leaves. The large calyxes are very sweet and resinous, as well as extremely psychoactive. Seeds are large, shortened, flattened, and ovoid in shape with a dark grey or reddish brown, mottled perianth or seed coat. The caruncle or point of attachment at the base of the seed is uncommonly deep and usually is surrounded by a sharpedged lip. Some individuals turn a very light yellow green in the flowering clusters as they mature under exposed conditions. Although they mature relatively late, they do seem to have met with acceptance in Great Britain and North America as drug strains. Seeds of many strains appear in small batches of low-quality African marijuana easily available in Amsterdam and other European cities. Phenotypes vary considerably, however, many are similar in appearance to strains from Thailand.

i) Mexico - (15 to 27 north latitude)

Mexico had long been the major source of marijuana smoked in America until recent years. Efforts by the border patrols to stop the flow of Mexican marijuana into the United States were only minimally effective and many varieties of high quality Mexican drug Cannabis were continually available. Many of the hybrid strains grown domestically today originated in the mountains of Mexico. In recent years, however, the Mexican government (with monetary backing by the United States) began an intensive program to eradicate Cannabis through the aerial spraying of herbicides such as Paraquat. Their program was effective, and high quality Mexican Cannabis is now rarely available. It is ironic that the NIMH (National Institute of Mental Health) is using domestic Mexican Cannabis strains grown in Mississippi as the pharmaceutical research product for
chemotherapy and glaucoma patients. In the prime of Mexican marijuana cultivation from the early 1960s to the middle 1970s, strains or "brands" of Cannabis were usually affixed with the name of the state or area where they were grown. Hence names like "Chiapan," "Guerreran," "Nayarit," "Michoacan," "Oaxacan," and "Sinaloan" have geographic origins behind their common names and mean something to this very day. All of these areas are Pacific coastal states extending in order from Sinaloa in the north at 27; through Nayarit, Jalisco, Michoacan, Guerrero, and Oaxaca; to Chiapas in the south at 15 - All of these states stretch from the coast into the mountains where Cannabis is grown.

Strains from Michoacan, Guerrero, and Oaxaca were the most common and a few comments may be ventured about each and about Mexican strains in general.

Mexican strains are thought of as tall, upright plants of moderate to large size with light to dark green, large leaves. The leaves are made up of long, medium width, moderately serrated leaflets arranged in a circular array. The plants mature relatively early in comparison to strains from Colombia or Thailand and produce many long floral clusters with a high calyx-to-leaf ratio and highly cerebral psychoactivity. Michoacan strains tend to have very slender leaves and a very high calyx-to-leaf ratio as do Guerreran strains, but Oaxacan strains tend to be broader-leafed, often with leafier floral clusters. Oaxacan strains are generally the largest and grow vigorously, while Michoacan strains are smaller and more delicate. Guerreran strains are often short and develop long, upright lower limbs. Seeds from most Mexican strains are fairly large, ovoid, and slightly flattened with a light colored grey or brown, unmottled perianth. Smaller, darker, more mottled seeds have appeared in Mexican marijuana during recent years. This may indicate that hybridization is taking place in Mexico, possibly with introduced seed from the largest seed source in the world, Colombia. No commercial seeded Cannabis crops are free from hybridization and great variation may occur in the offspring. More recently, large
amounts of hybrid domestic seed have been introduced into Mexico. It is not uncommon to find Thai and Afghani phenotypes in recent shipments of Cannabis from Mexico.

j) Morocco/Rif mountains - (35 north latitude)

The Rif mountains are located in northernmost Morocco near the Mediterranean Sea and range up to 2,500 meters (8,000 feet). On a high plateau surrounding the city of Ketama grows most of the Cannabis used for kif floral clusters and hashish production. Seeds are broad-sown or scattered on rocky terraced fields in the spring, as soon as the last light snows melt, and the mature plants are harvested in late August and September. Mature plants are usually 1 to 2 meters (4 to 6 feet) tall and only slightly branched. This results from crowded cultivation techniques and lack of irrigation. Each pistillate plant bears only one main terminal flower cluster full of seeds. Few staminate plants, if any, are pulled to prevent pollination. Although Cannabis in Morocco was originally cultivated for floral clusters to be mixed with tobacco and smoked as kif, hashish production has begun in the past 30 years due to Western influence. In Morocco, hashish is manufactured by shaking the entire plant over a silk screen and collecting the powdery resins that pass through the screen. It is a matter of speculation whether the original Moroccan kif strains might be extinct. It is reported that some of these strains were grown for seedless flower production and areas of Morocco may still exist where this is the tradition.

Because of selection for hashish production, Moroccan strains resemble both Lebanese and Hindu Kush strains in their relatively broad leaves, short growth habit, and high resin production. Moroccan strains are possibly related to these other Cannabis indica types.

k) Nepal - (26 to 30 north latitude)

Most Cannabis in Nepal occurs in wild stands high in the Himalayan foothills (up to 3,200 meters [10,000 feet]). Little Cannabis is cultivated, and it is from select wild plants that most Nepalese hashish and marijuana originate. Nepalese plants are usually tall and thin with long, slightly branched limbs. The long, thin flowering tops are very aromatic and reminiscent of the finest fresh "temple ball" and "finger" hashish hand-rubbed from wild plants. Resin production is abundant and psychoactivity is high Few Nepalese strains have appeared in domestic Cannabis crops but they do seem to make strong hybrids with strains from domestic sources and Thailand.

I) Russian - (35 to 60 north latitude) Cannabis ruderalis (uncultivated)

Short stature (10 to 50 centimeters [3 to 18 inches]) and brief life cycle (8 to 10 weeks), wide, reduced leaves and specialized seeds characterize weed Cannabis of Russia. Janischewsky (1924) discovered weedy Cannabis and named it Cannabis ruderalis. Ruderalis could prove valuable in breeding rapidly maturing strains for commercial use in temperate latitudes. It flowers when approximately 7 weeks old without apparent dependence on daylength. Russian Cannabis ruderalis is nearly always high in CBD and low in THC.

m) South Africa - (22 to 35 south latitude)

Dagga of South Africa is highly acclaimed. Most seeds have been collected from marijuana shipments in Europe. Some are very early-maturing (September in northern latitudes) and sweet smelling. The stretched light green floral clusters and sweet aroma are comparable to Thai strains.

n) Southeast Asia - Cambodia, Laos, Thailand and Vietnam (10 to 20 north latitude)

Since American troops first returned from the war in Vietnam, the Cambodian, Laotian, Thai, and Vietnamese strains have been regarded as some of the very finest in the world. Currently most Southeast Asian Cannabis is produced in northern and eastern Thailand. Until recent times, Cannabis farming has been a cottage industry of the northern mountain areas and each family grew a small garden. The pride of a farmer in his crop was reflected in the high quality and seedless nature of each carefully wrapped Thai stick. Due largely to the craving of Americans for exotic
marijuana, Cannabis cultivation has become a big business in Thailand and many farmers are growing large fields of lower quality Cannabis in the eastern lowlands. It is suspected that other Cannabis strains, brought to Thailand to replenish local strains and begin large plantations, may have
hybridized with original Thai strains and altered the resultant genetics. Also, wild stands of Cannabis may now be cut and dried for export.

Strains from Thailand are characterized by tall meandering growth of the main stalk and limbs and fairly extensive branching. The leaves are often very large with 9 to 11 long, slender, coarsely serrated leaflets arranged in a drooping hand like array. The Thai refer to them as "alligator
tails" and the name is certainly appropriate.

Most Thai strains are very late-maturing and subject to hermaphrodism. It is not understood whether strains from Thailand turn hermaphrodite as a reaction to the extremes of northern temperate weather or if they have a genetically controlled tendency towards hermaphrodism. To the dismay of many cultivators and researchers, Thai strains mature late, flower slowly, and ripen unevenly. Retarded floral development and apparent disregard for changes in photoperiod and weather may have given rise to the story that Cannabis plants in Thailand live and bear flowers for years. Despite these shortcomings, Thai strains are very psychoactive and many hybrid crosses have been made with rapidly maturing strains, such as Mexican and
Hindu Kush, in a successful attempt to create early-maturing hybrids of high psychoactivity and characteristic Thai sweet, citrus taste. The calyxes of Thai strains are very large, as are the seeds and other anatomical features, lead- ing to the misconception that strains may be polyploid. No natural polyploidy has been discovered in any strains of Cannabis though no one has ever taken the time to look thoroughly. The seeds are very large, ovoid, slightly flattened, and light brown or tan in color. The perianth is never mottled or striped except at the base. Greenhouses prove to be the best way to mature stubborn Thai strains in temperate climes.

3. Hybrid Drug Phenotypes

a) Creeper Phenotype - This phenotype has appeared in several domestic Cannabis crops and it is a frequent phenotype in certain hybrid strains. It has not yet been determined whether this trait is genetically controlled (dominant or recessive), but efforts to develop a true-breeding strain of creepers are meeting with partial success. This phenotype appears when the main stalk of the seedling has grown to about 1 meter (3 feet) in height. It then begins to bend at approximately the middle of the stalk, up to 700 from the vertical, usually in the direction of the sun. Subsequently, the first limbs sag until they touch the ground and begin to grow back up. In extremely loose mulch and humid conditions the limbs will occasionally root along the bottom surface. Possibly as a result of increased light exposure, the primary limbs continue to branch once or twice, creating wide frond-like limbs of buds resembling South Indian strains. This phenotype usually produces very high flower yields. The leaves of these creeper phenotype plants
are nearly always of medium size with 7-11 long, narrow, highly serrated leaflets.

b) Huge Upright Phenotype - This phenotype is characterized by medium size leaves with narrow, highly serrated leaflets much like the creeper strains, and may also be an acclimatized North American phenotype. In this phenotype, however, a long, straight central stalk from 2 to 4 meters (6.5 to 13 feet) tall forms and the long, slender primary limbs grow in an upright fashion until they are nearly as tall or occasionally taller than the central stalk. This strain resembles the Hindu Kush strains in general shape, except that the entire domestic plant is much larger than the Hindu Kush with long, slender, more highly branched primary limbs, much narrower leaflets, and a higher calyx-to-leaf ratio. These huge upright strains are
also hybrids of many different imported strains and no specific origin may be determined.

The preceding has been a listing of gross phenotypes for several of the many strains of Cannabis occurring worldwide. Although many of them are rare, the seeds appear occasionally due to the extreme mobility of American and European Cannabis enthusiasts. As a consequence of this
extreme mobility, it is feared that many of the world's finest strains of Cannabis have been or may be lost forever due to hybridization with foreign Cannabis populations and the socio-economic displacement of Cannabis cultures worldwide. Collectors and breeders are needed to preserve
these rare and endangered gene pools before it is too late.

Various combinations of these traits are possible and inevitable. The traits that we most often see are most likely dominant and the improvement of Cannabis strains through breeding is most easily accomplished by concentrating on the dominant phenotypes for the most important traits. The best breeders set high goals of limited scope and adhere to their ideals.

All Information stated in this post is copied verbatim from chapter 3 of -Marijuana Botany-
An Advanced Study: The Propagation and Breeding of Distinctive Cannabis
by Robert Connell Clarke


Everyone who hasn't read this before should check out the land race strain info starting with Colombian strains highlighted in orange............It dope indeed.


Premium Member
Nice post Mizz Elvis. I have the book and it's great reference material. Starting to get a bit dogeared from use. :damnhippie:


Great Miss Elvis!

RCC is a good read for anyone interested in landraces and what was characterized as certain strains of cannabis.



Good read. Anybody know what year that was published? I'm thinking around 1980?


^^near as dammit pinekreek...1981 :).Don't think this one has been bettered yet, really comprehensive reading.


Premium Member
I was gonna start a fav book thread and list that one as my favorite. I saw this on my dad's coffee table when I was 12. It was my first visit to see him. I could read.... and I was like what???

When I was 26 I saw this book on Amazon or something, recognized it and got it. Put it to good use as my dad had done many years prior. This is where I learned to tell when my plants were mature and all kinds of other good stuff.

Great post Mizz Elvis!!


This looks like a great book. Been meaning to buy it. Gonna go buy a copy on Amazon right now ;)

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