Chapter 2

Cannabis is unique in many ways. Of all plants, it is the only genus known to produce chemical substances known as cannabinoids. The cannabinoids are the psychoactive ingredients of marijuana; they are what get you high. By 1974, 37 naturally occurring cannabinoids had been discovered 115,118. Most of the cannabinoids appear in very small amounts (less than .01 percent of total cannabinoids) and are not considered psychoactive, or else not important to the high. Many are simply homologues or analogues (similar structure or function) to the few major cannabinoids which are listed.

1. (-)-delta 9-trans-tetrahydrocannabinol ((There are several numbering systems used for cannabinoids. The system in this book is most common in American publications and is based on formal chemical rules for numbering pyran compounds. Another common system is used more by Europeans and is based on a monoterpenoid system which is more useful considering the biogenesis of the compound.)) This (delta-9 THC) is the main psychotomimetic (mindbending) ingredient of marijuana. Estimates state that 70 to 100 percent (121) of the marijuana high results from the delta-9 THC present. It occurs in almost all Cannabis in concentration that vary from traces to about 95 percent of all the cannabinoids in the sample. In very potent varieties, carefully prepared marijuana can have up to 12 percent delta-9 THC by dry weight of the sample (seeds and stems removed from flowering buds). (("Buds" of commercial marijuana is the popular name given to masses of female flowers that form distinct clusters.))

1. Delta-8 THC - This substance is reported in low concentration, less than one percent of the delta-9 THC present. Its activity is slightly less than that of delta-9 THC. It may be an artefact of the extraction/analysis process. Here we refer to delta-9 THC and delta-8 THC as THC.

2. Cannabidiol - CBD also occurs in almost all varieties. Concentration range from nil (119,138), to about 95 percent of the total cannabinoids present. THC and CBD are the two most abundant naturally occurring cannabinoids. CBD is not psychotomimetic in the pure form (192), although it does have sedative, analgesic, and antibiotic properties. In order for CBD to affect the high, THC must be present in quantities ordinarily psychoactive. CBD can contribute to the high by interacting with THC to potentiate (enhance) or antagonise (interfere or lessen) certain qualities of the high. CBD appears to potentiate the depressant effects of THC and antagonise is excitatory effects (186). CBD also delays the onset of the high (183) but can make it last considerably longer (as much as twice as long). (The grass takes a while to come on but keeps coming on.) Opinions are conflicting as to whether it increases or decreases the intensity of the high, "intensity" and high" being difficult to define. Terms such as knock-out or sleepy, dreamlike, or melancholic are often used to describe the high from grass with sizeable proportions of CBD and THC. When only small amounts of THC are present with high proportions of CBD, the high is more of a buzz, and the mind feels dull and the body de-energised.

{See Figure 11 to 16 for chemical structure in monochrome bitmap format.}

3. Cannabinol - CBN is not produced by the plant per se. It is the degradation (oxidative) product of THC. Fresh samples of marijuana contain very little CBN but curing, poor storage, or processing such as when making hashish, can cause much of the THC to be oxidised to CBN. Pure forms of CBN have at most 10 percent of the psychoactivity of THC (192). Like CBD, it is suspected of potentiating certain aspects of the high, although so far these affects appear to be slight (183,185). CBN seems to potentiate THC's disorienting qualities. One may feel more dizzy or drugged or generally untogether but not necessarily higher. In fact, with a high proportion of CBN, the high may start well but feels as if it never quite reaches its peak, and when coming down one feels tired or sleepy. High CBN in homegrown grass is not desirable since it represents a loss of 90 percent of the psychoactivity of its precursor THC.

4. Tetrahydrocannabivarin - THCV is the propyl homologue of THC. In the aromatic ring the usual five-carbon pentyl is replaced by a short three-carbon propyl chain. The propyl cannabinoids have so far been found in some varieties originating from Southeast and Central Asia and parts of Africa. What are considered some very potent marijuana varieties contain propyl cannabinoids. In one study, THCV made up to 48.23 percent (Afghanistan strain) and 53.69 percent (South Africa) of the cannabinoids found (136). We've seen no reports on its activity in humans. From animal studies it appears to be much faster in onset and quicker to dissipate than THC (181). It may be the constituent of one- or two-toke grass, but its activity appears to be somewhat less than that of THC.

The propyl cannabinoids are a series corresponding to the usual pentyl cannabinoids. The counterpart of CBD is CBDV; and of CBN, CBV. There are no reports on their activity and for now we can only speculate that they are similar to CBD and CBN. Unless noted otherwise, in this book THC refers collectively to delta-9 THC, delta-8 THC, and THCV.

5. Cannabichromene - CBC is another major cannabinoid, although it is found in smaller concentrations than CBD and THC. It was previously believed that is was a minor constituent, but more exacting analysis showed that the compound often reported as CBD may actually be CBC (119,137). However, relative to THC and CBD, its concentration in the plants is low, probably not exceeding 20 percent of total cannabinoids. CBC is believed not to be psychotomimetic in humans (121); however, its presence in plants is purportedly very potent has led to the suspicion that it may be interacting with THC to enhance the high (137). Cannabicyclol (CBL) is a degradative product like CBN and CBV (123). During extraction, light converts CBC to CBL. There are no reports on its activity in humans, and it is found in small amounts, if at all, in fresh plant material.

Cannabinoids and the High

The marijuana high is a complex experience. It involves a wide range of psychical, physical, and emotional responses. The high is a subjective experience based in the individual - one's personality, mood, disposition, and experience with the drug. Given the person, the intensity of the high depends primarily on the amount of THC present in the marijuana. Delta-9 THC is the main ingredient of marijuana and must be present in sufficient quantities for a good marijuana high. People who smoke grass that has very little cannabinoids other then delta-9 THC usually report that the high is very intense. Most people will get high from a joint having delta-9 THC of .5 percent concentration to material. Grass having a THC concentration of three percent would be considered excellent quality by anyone's standards. In this book, for brevity, we use potency to mean the sum effects of the cannabinoids and the overall high induced.

Marijuana (plant material) is sometimes rated more potent that the content of delta-9 THC alone would suggest. It also elicits qualitatively different highs. The reasons for this have not been sorted out. Few clinical studies with known combinations of several cannabinoids have been undertaken with human subjects. This field is still in its infancy. So far, different highs and possibly higher potency seem to be due to the interaction of delta-9 THC and other cannabinoids (THCV,CBD,CBN, and possibly CBC). Except for THCV, in the pure form, these other cannabinoids do not have much psychoactivity.

Another possibility for higher potency is that homologues of delta-9 THC with longer side chains at C-3 (and higher activity) might be found in certain marijuana varieties. Compounds with longer side chains have been mode in laboratories and their activity is sometimes much higher, with estimates over 500 times that of natural delta-9 THC (55,113,191). Compounds besides THCV with shorter chains (methyl (139) and butyl (118)) in this position have been found in small amounts in some marijuana samples, indicating that variations do exist. However, this is not a very likely explanation. More likely, THCV is more prevalent in marijuana than supposed and probably had additive or synergistic effects with delta-9 THC.

The possibility that there are non-cannabinoids that are psychoactive or interacting with the cannabinoids has not been investigated in detail. Non-cannabinoids with biological activity have been isolated from the plants, but only in very small quantities (181). None are known to be psychotomimetic. However, they may contribute to the overall experience in non-mental ways, such as the stimulation of the appetite.

Different blends of cannabinoids account for high of different qualities. The intensity of the high depends primarily on the amount of delta-9 THC present and on the method of ingestion. A complex drug such as marijuana affects the mind and body in many ways. Sorting out what accounts for what response can become quite complex. The methodology to isolate and test the different cannabinoids now exists. The National Institute of Mental Health (NIMH) is funding research on the pharmacology of marijuana. However, such research is paltry, considering that over 30 million people in the United States use the crude drug. Much more research is needed before definite understanding of the cannabinoids and the high is attained.

When the legal restriction are removed, marijuana will probably be sold by particular blends of cannabinoids and standard amounts of delta-9 THC. Synthetic marijuana will probably be made with homologues of delta-9 THC that have much higher activity than the natural form. For now, without access to a lab, you must be satisfied with your own smoking evaluation (for research purposes only), ultimately the most important criterion any way.

Resin and Resin Glands

Many people consider potency and resin concentration synonymous. People hear of plants oozing or gushing with copious resin, and the image is of resin flowing in the plant like the latex of a rubber tree or the sap of a maple tree. But these visions are just pipe dreams.

It is quite possible to have a resinous plant with little potency or a plant with little apparent resin which is very potent. Potency depends primarily on the concentration of THC in the plant material. Many more substances besides the cannabinoids make up the crude resin of Cannabis. Preparations such as ghanja or hashish are roughly about one-third by weight non-psychoactive water-soluble substances and cellular debris. Another third is non-psychoactive resins such as phenoloic and terpenoid polymers, glycerides, and triterpenes. Only one-fourth to one-third is the cannabinoids. In many Cannabis plants, THC may be only a very small percentage of the total cannabinoids. ((These figures are very approximate. Actual percentages depend on sample material, processing, and extraction procedures. See Table 8 and 9 for percentages of THC in hashish.)) The remainder (5 to 10 percent) of the resin will be essential oils, sterols, fatty acids, and various hydrocarbons common to plants.

The cannabinoids basically do not flow in the plant, nor are they the plant's sap. About 80 to 90 percent of the cannabinoids are synthesised ad stored in microscopic resin glands that appear on the outer surfaces of all plant parts except the root and seed. the arrangement and number (concentration) of resin glands vary somewhat with the particular strain examined. Marijuana varieties generally have more resin glands, and they are larger then resin glands on non-drug varieties.

Although resin glands are structurally diverse, they are of three basic types. The bulbous type is the smallest (15-30 um ((um is the symbol for a micrometer (or micron), equal to 1/1,000,000 of a meter, or approximately 1/25,000 of an inch.)) or about .0006 to .0012 inches). From one to four cells make up the "foot" and "stalk," and one to four cells make up the "head" of the gland (25). Head cells secrete a resin - presumably cannabinoids - oils, and related compounds which accumulate between the head cells and the outer membrane (cuticle). When the gland matures, a nipple-like outpocket may form on the membrane from the pressure of the accumulating resin. The bulbous glands are found scattered about the surfaces of the above-ground plant parts.

The second type of gland is much larger and more numerous than the bulbous glands. The are called "capitate," which means having a globular-shaped head. On immature plants, the heads lie flush or appear not to have a stalk and are called "capitate sessile." They actually have a stalk that is one cell high, although it may not be visible beneath the globular head. The head is composed of usually eight, but up to 16 cells, that form a convex rosette. These cells secrete a cannabinoid-rich resin which accumulates between the rosette and its outer membrane. This gives it a spherical shape, and the gland measures from 25 to 100 um across. In fresh plant material about 80 to 90 percent of their contents will be cannabinoids, the rest primarily essential oils (146).

During flowering the capitate glands that appear on the newly formed plant parts take on a third form. Some of the glands are raised to a height of 150 to 500 um when their talks elongate, possibly due to their greater activity. The stalk is composed mostly of adjacent epidermal tissue. These capitate-stalked glands appear during flowering and form their densest cover on the female flower bracts. They are also highly concentrated on the small leaves that accompany the flowers of fine marijuana varieties. Highest concentration is along the veins of the lower leaf surface, although the glands may also be found on the upper leaf surface on some varieties. The male flowers have stalked glands on the sepals, but they are smaller and less concentrated than on the female bracts. Male flowers form a row of very large capitate glands along the opposite sides of anthers.

Capitate-stalked resin glands are the only ones visible without a microscope. To the naked eye, this covering of glands on the female flower bracts looks like talcum or dew sprinkled on a fuzzy surface. With a strong hand lens, the heads and stalks are distinct. Resin glands also can be seen on the anthers of the male flowers and on the undersides of the small leaves the intersperse the flower clusters.

{Figure 17. Upper surface of a small leaf, showing stalked glands.} {Figure 18. Resin glands on a stem lie close to the surface beneath the cystolith hairs. Hairs always point in direction of growing shoots.}

Resin glands are not visible until flowers form. The more obvious covering of white hairs seen on stems, petioles, and leaves are not resin glands. They are cystolith hairs of carbonate and silicate which are common to many plants. These sharp-pointed hairs afford the plant some protection from insects and make it less palatable to larger, plant-eating animals.

In India, to make the finest quality hashish (nup), dried plants are thrashed over screens. Gland heads, stalks and trichomes collect in a white to golden powder which is then compressed into hashish (for hashmaking search section 21 for "hash").

Resin rarely accumulates in the copious quantities people would lead you to believe. Actually, the plants form a cover of resin glands rather than a coating of resin. Usually this is no more apparent than for the female flowers to glisten with pin-points of light and for the leaves and stems to feel a bit sticky when you run your fingers over them.

On some fine marijuana strains, resin may become obvious by the end of flowering and seed set. Resins occasionally secrete through pores in the membrane of gland heads. Usually secretion occurs many weeks after the stalked glands appear. The glands seem to empty their contents, leaving hollow spaces (vacuoles) in the stalk and head cells. After secretion, the glands cease to function and begin to degenerate. Gland heads, stalks, and trichomes become clumped together, and the whole flowering surface becomes a sticky mass. For reasons we'll go into later, this is not necessarily desirable. (see sections 20,21.)

Small quantities of cannabinoids are present in the internal tissues of the plant. The bulk is found in small single cells (non-articulated laticifers) that elongate to form small, individual resin canals. The resin canals ramify the developing shoots, and penetrate the plant's conducting tissue (phloem). Minute clumps of resin found in the phloem are probably deposited by these resin canals. Other plant cells contain insignificant amounts of cannabinoids and probably a good 90 percent of the cannabinoids are localised in the resin glands.

Cannabinoid synthesis seems to occur primarily in the head and apex of the stalk cells of the resin glands (26). Lacticifers and possibly other plant cells probably contribute by synthesising the simpler molecules that will eventually make up the cannabinoids. Biosynthesis (the way the plant makes the molecules) of the cannabinoids is believed to follow a scheme originally outlined by A.R. Todd in his paper "Hashish," published in 1946 (see Figure 19). In the 1960s the pathway was worked out by Raphal Mechoulam, and confirmed in 1975 by Dr. Shimomura and his associates.

{Figure 19. Possible biosynthesis of cannabinoids.}

Notice that all the cannabinoids are their acid forms with a (COOH) carboxyl group at C-2 in the aromatic ring. This group may also appear at C-4 and the compounds are called, for example, THC acid "A" and THC acid "B", respectively. The position of the carboxyl group does not affect the potency, but, in fact, in their acid forms the cannabinoids are not psychoactive. In fresh plant material, cannabinoids are almost entirely inn their acid forms. The normal procedure of curing and smoking the grass (heat) removes the carboxyl group, forming the gas CO2 and the psychoactive neutral cannabinoids. Removing the CO2 in important only if you plan to eat the marijuana. It is then necessary to apply heat (baking in brownies, for example) for the cannabinoids to become psychoactive. Ten minutes of baking marijuana at 200F is enough to convert the THC acids to neutral THC.

The formation of CBG acid, from which all the other cannabinoids are formed, is initially made from much simpler compounds containing terpene units. The example here is olivetolic acid condensing with a terpene moiety called geranyl pyrophosphate. It is not known whether these are the actual or only precursors to CBG in the living plant.

Terpenes and related substances are quite light and some of them can be extracted by steam distillation to yield the "essential oil" of the plant (from essence - giving the flavour, aroma, character). Over 30 of these related oily substances have been identified from Cannabis (143). On exposure to light and air, some of the polymerise, forming resins and tars.

The cannabinoids are odourless; most of the sweet, distinctive, pleasant "minty" fragrance and taste of fresh marijuana comes from only five substances which make up only 5 to 10 percent of the essential oils: the mono- and sesqui-terpenes alpha- and beta-pinene, limonene, myrcene, and beta-phalandrene (144). These oily substances are volatile and enter the air quickly, dissipating with time. Subsequently, the marijuana loses much of its sweetness and minty bouquet.

The essential oils constitute about .1 to .3 percent of the dry weight of a fresh marijuana sample, or on the order of 10 percent of the weight of the cannabinoids. Essential oils are found within the heads of the resin glands and make up about 10 to 20 percent of their contents in fresh material (146). They have also been detected in the resin canals (laticifers) (31).

Different samples of Cannabis have essential oils of different composition. This is not surprising given the variability of the plant. Since substances found in the essential oils are, or are related to, substances that are the precursors of the cannabinoids, there is some chance that a relationship exists between a particular bouquet and cannabinoids content. No such relationship is yet known, but it has only been studied superficially. When connoisseurs sample the bouquet of a grass sample, they are basically determining whether it is fresh. Fresh grass mean fresh cannabinoids and less of these are likely to have been degraded to non-psychoactive products.

Production of Cannabinoids by Cannabis

Why Cannabis produces cannabinoids and resins is a question probably every grower has wondered about. Supposedly, if you know, you could stimulate an environmental factor to increase cannabinoids production. Unfortunately, it does not follow that increasing a particular selective pressure will affect a plant's (phenotype) cannabinoids production. However, over a period of generations, it is possible that environmental manipulations can increase the overall cannabinoids concentrations in a population of plants. But even this procedure would work slowly compared to direct breeding by the farmer.

From the microstructure of the resin glands and the complexity of the resin, it is apparent that Cannabis invests considerable energy in making and storing the cannabinoids. Obviously, the cannabinoids are not a simple by-product or excretory product. No doubt the cannabinoids and resins serve the plant in many ways, but probably they have more to do with biotic factors (other living things) rather than abiotic factors (non-living environment such as sunlight, moisture, etc.).

The cannabinoids, resins, and related substances make up a complex and biologically highly active group of chemicals, a virtual chemical arsenal from which the plant draws its means for dealing with other organisms. This would apply especially to herbivores, pathogens, and competing plants. In the case of humans, the cannabinoids are an attractant. Some possible advantages to the plant are listed below, but no direct studies have been done on this question. Indeed, it is surprising that botanists have shown so little interest in this question; they have even gone out of their way to state their lack of interest.

Possible Advantages of Cannabinoid Production

1. Obviously the cannabinoids are psychoactive and physiologically active in many animals. This may dissuade plant-eating animals from eating the plant, especially the reproductive parts.

Many birds enjoy Cannabis seeds (guaranteed to make your canary sing). But in nature, birds will not bother young seeds, probably because they are encased in the cannabinoids-rich bracts. In wild or weedy plants, when the seed is mature it "shells out" and falls to the ground. Birds will eat the naked seeds. However, matured seeds are quite hard. Many will not be cracked and eventually will be dropped elsewhere, helping the plant to propagate. Bees and other insects are attracted to the pollen. The cannabinoids and resins may deter insects from feeding on pollen and developing seeds. Resin glands reach their largest size on the anthers (which hold pollen) and bracts (which contain the seed). {See plates 6, 7, 10 and 11.}

2. Terpenoid and phenolic resins are known to inhibit germination of some seeds. Cannabis resins may help Cannabis seedlings compete with other seedlings by inhibiting their germination.

3. Many of the cannabinoids (CBD, CBG, CBC and their acids) are highly active antibiotics against a wide range of bacteria (almost all are gram +) (36,130,184). Crude resin extracts have been shown to be nematocidal (36). (However, fungicidal activity is low.)

Most of the explanations you've probably heard for resin production from both lore and scientists have to do with physical factors such as sunlight, heat, and dryness. Presumably the resin coats the plant, protecting it from drying out under physical extremes. These explanations make little sense in light of the resins' chemistry.

The physical qualities of the glands and resins probably aid the plant in some ways. The sticky nature of resin may help pollen grains to adhere to the flowering mass and stigmas, or simply make the plant parts less palatable. And gland heads do absorb and reflect considerable sunlight, and so possibly protect the developing seed. For instance, gland heads are at first colourless (i.e., they absorb ultraviolet light). This screening of ultraviolet light, a known mutagen, may lower possible deleterious mutations. But physical properties seem to be secondary to the resins' chemical properties as functional compounds to the plant.

Cannabis Chemotypes

All Cannabis plants produce some cannabinoids. Each strain produces characteristic amounts of particular cannabinoids. Strains differ in the total amounts they contain. Usually they average about three percent cannabinoids to dry weight, but concentrations range from about one to 12 percent cannabinoids in a cleaned (seeds and stems removed), dried bud. Strains also differ in which cannabinoids they produce. Based on which cannabinoids, Cannabis strains can be divided into five broad chemical groups.((Chemical classification based on work by Small et al (51))) The general trend is for plants to have either THC or CBD as the main cannabinoid.

Type I

Strains are high in THC and low in CBD. This type represents some of the finest marijuana strains. They usually originate from tropical zones below 30 degrees latitude, which in the north runs through Houston and New Orleans to Morocco, North India, and Shanghai, and in the south through Rio de Janeiro, South Africa, and Australia. Most of the high-quality marijuana from Mexico, Jamaica, and Colombia sols in this country is this type; most of you will grow this type. As with all five chemical types, type I comes in different sizes and shapes. Most common are plant about 10 to 12 feet tall (outdoors), quite bushy, with branches that grow outward to form the plant into a cone (Christmas tree shape). Other tall varieties (to 18 feet) have branches that grow upward (poplar-tree shaped - some Mexican, Southeast and Central Asian varieties). A less common short variety (up to eight feet) develops several main stems and the plants appear to sprawl (Mexico, India).

Type II

This is an intermediate group, with high CBD and moderate to high THC. They usually originate from countries bordering 30 degrees latitude, such as Morocco, Afghanistan and Pakistan. In this country, this type of grass usually comes from Afghani and Colombian varieties. Type II plants are quite variable in the intensity and quality of the high they produce, depending on the relative amounts of THC and CBD in the variety. Probably because of their high CBD and overall resin content, these plants are often sued to prepare hashish and other concentrated forms of marijuana.

The most common varieties grow to about eight to 12 feet and assume a poplar-tree shape with long branches that grow upward from the stem base and much shorter branches toward the top. They usually come from Turkey, Greece, and Central or Southeast Asia and occasionally from Colombia and Mexico. Some varieties are shorter, about four to eight feet at maturity, and very bushy with a luxuriant covering of leaves. These usually originate from Nepal, northern India, and other parts of Central Asia as well as North Africa. Other varieties appear remarkably like short (five to seven feet) hemp plants, with straight, slender stems and small, weakly developed branches (Vietnam). A common short variety, less than four feet tall (Lebanon, N. Africa), forms a continuous dense cluster of buds along its short stem. They appear remarkably like the upper half of more common marijuana plants.

{Figure 20. Left: This Pakistani variety ("indica") reaches a height of five feet (large leaves removed). Right: Flowering top two months later.}

Type III

Plants are high in CBD and low in THC. These are often cultivated for hemp fibre or oil seed. Usually they originate from countries north of 30 degrees latitude. As marijuana they yield a low-potency grass and are considered non-drug varieties. If you choose your seeds from potent grass, it will not be this type. An example of these plants are Midwestern weedy hemps which are often collected and sold for low-grade domestic grass. The high CBD content can make you feel drowsy with a mild headache long before you feel high. These plants are very diverse morphologically even when categorised by cultivated types. Hemp plants are usually tell (eight to 20 feet) with an emphasis on stem development and minimal branching. Starting from the base, long, even internodes (stem portion from one set of leaves to the next pair) and opposite phyllotaxy (see 3.2) cover a good portion of the stem. Some varieties form long, sparse branches only on the upper portion of the stem (many Midwest weeds). Other varieties (Kentucky hemp) are the familiar Christmas-tree shape.

Seed varieties are usually short (two to eight feet) and very bushy. Branches on some are short, grow outward and are all of approximately the same length, giving the plant a cylindrical shape. Some of the shorter (two to three feet) seed varieties have undeveloped branches, and almost all of the seeds collect in a massive cluster along the top portion of the stalk. Seed plants are often the most unusual-appearing of Cannabis plants, and you won't find them in the United States.

As expected, the figures for average THC in Midwestern weeds are quite low. this is consistent with their reputation for low potency. But the range of THC goes up to 2.37 percent in the Illinois study. This is comparable with some of the higher-quality imported marijuana and is consistent with some people's claims that Midwestern weeds provided them with great highs.

Type IV

Varieties that produce propyl cannabinoids in significant amounts (over five percent of total cannabinoids) form a fourth group from both type I and II plants. Testing for the propyl cannabinoids has been limited and most reports do not include them. They have been found in plants from South Africa, Nigeria, Afghanistan, India, Pakistan, and Nepal with THCV as high as 53.69 percent of total cannabinoids (136). They usually have moderate to high levels of both THC and CBD and hence have a complex cannabinoid chemistry. Type IV plants represent some of the world's more exotic marijuana varieties.

A fifth type, based on the production of CBGM, which is not psychoactive, is found in northeastern Asia, including Japan, Korea and China. This type is not relevant to us and will not be mentioned again.

There are many different techniques for sampling, extraction, and estimation of cannabinoids in plant material. To minimise differences among research groups, the above data (except for Midwestern weedy hemps) are taken from studies at the University of Mississippi at Oxford (66,119,136).

Unfortunately, some of the best Colombian, Mexican and Thai varieties are not included in the data. Many of these have not been tested until recently, and the figures are not yet published. Under the system for testing at the University of Mississippi, the highest THC variety reached six to eight percent THC in a bud. These seeds originated from Mexico.

{See Table01 to 10.}

These five chemical types are not distinct entities; that is, each type contains several quite different-appearing varieties. Actually, varieties of different types may look more similar than varieties from the same type. But the ability to produce characteristic amounts of particular cannabinoids is genetically based. This means the each type contains certain genes and gene combinations in common, and in biological terms, the plants are called chemical genotypes.

These types may be from virtually any country simply because of the plant's past and ongoing history of movement. the first three can be found in most countries where Cannabis is heavily cultivated, although marijuana plants (types I, II, IV) usually originate from lower latitudes nearer the equator. This may be simply explained in terms of cultural practices. Marijuana traditionally has been cultivated in southerly cultures such as India, Southeast and Central Asia, Africa; and in the West in Mexico, Colombia, Jamaica, and Central American countries. On the other hand, useful characteristics must exist before cultures can put them to use after selection. And the characteristic (drug or fibre) must maintain itself within the local environment (see 18.4).

Non-drug types (type III) usually originate at higher latitudes with shorter growing seasons. A definite gradation exists for non-drug to drug types, starting in temperate zones and moving toward the equator. The same gradation may be found for the appearance of propyl cannabinoids toward the equator. This doesn't mean that the quality of the grass you grow depends on whether you live in the north or south, but that over a period of years and decades, a group of plants may drift toward either the drug or the non-drug type (either rich in THC or rich in CBD).

The majority of the marijuana sold in the United States has less than one percent THC; and the bulk of this comes from Mexican and domestic sources. The highest percentages of THC in marijuana that we've seen are: Colombian (9.7), Mexican (13.2), Hawaiian (7.8), and Thai sticks (20.2; however, this is believed to be adulterated with hash oil). The percentages of THC reported vary greatly, because they depend on the particular method of sampling and estimation used.

Five samples of Colombian Golds, bought in New York City and San Francisco for from $30 to $50 (1976) an ounce, averaged 2.59 percent THC and 1.27 percent CBN. The CBN represents an average of about one-third of the THC originally present in the fresh plant by the time it reaches American streets. This is one advantage that homegrowers have, since their marijuana is fresh. In fresh plant material, less than 10 percent of the THC will have been converted to CBN, as long as the material is properly harvested, cured, and stored.

By the time hashish reaches the American market, THC content is usually at the low end of the ranges given here, usually between 1.5 and 4 percent THC. The darker outer layer of hashish is caused by deterioration. The inner part will contain the highest concentration of THC.

The average range for hash oil and red oil is 12 to 25 percent when it is fresh. It is not uncommon for illicit hash oil to have more than 60 percent THC. However, light, as well as air, very rapidly decomposes THC in the oil form (see the section on "Storage" in section 21). You can't tell whether the oil will be wondrous or worthless unless you smoke it.

The preparations listed in Tables 9 and 10 are relatively fresh compared to hashish on the American market. Total cannabinoids make up roughly 25 to 35 percent by weight of hashish and resin preparations. Note that the data in these tables are relative concentrations.

The very high figures for CBN in hashish indicate that much of the THC is converted to CBN because of processing and aging. During hashmaking many of the gland heads are broken and the THC is exposed to light and air. The figures in these tables are typical of what to expect for relative concentrations of THC in hashish on the American market. Actual concentrations are roughly one-fourth to one-third of these figures.

Obviously, THC percentages for hashish and tinctures are not that high compared to fine marijuana. Hashish in the United States seldom lives up to its reputation. The best buy in terms of the amount of THC for the money is hash oil when it is high quality and fresh. More often a fine homegrown sinsemilla or sometimes a lightly seeded Colombian is the best investment. (Of course, the best value is always what you grow yourself.)