Marijuana Potency

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Marijuana Potency

Post by Weedguru Higher » Mon Mar 15, 2010 11:22 pm

Marijuana Potency

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Whether marijuana is more potent today than it was 30 or 40 years ago is at the center of much debate. The U.S. federal government has released information saying that the levels of potency have risen anywhere from 10 to 25 times since the 1960s. Is this a myth or reality?

­"There's no question that marijuana, today, is more potent than the marijuana in the 1960s. However, if you were to look at the average marijuana potency which is about 3.5 percent, it's been relatively stable for the last 20 years. Having said that, it's very important that what we have now is a wider range of potencies available than we had in the 1970s, in particular," Director of the National Institute on Drug Abuse Alan Leshner said in 1999 while testifying in front of the U.S. House Subcommittee on Crime.

Those who support the legalization of marijuana say that the data is skewed because testing was only performed on marijuana of specific geographic origins in the 1960s and 1970s, and therefore isn't representative of marijuana potency overall. Officials obtained the samples from a type of Mexican marijuana that is known to contain low levels of THC -- 0.4 to 1 percent. When these levels are compared to other types of marijuana, it looks as if potency levels have risen in the last 30 years.

Typical THC levels, which determines marijuana potency, range from 0.3 to 4 percent. However, some specially grown plants can contain THC levels as high as 15 percent. Several factors are involved in determining the potency of a marijuana plant, including:

* Growing climate and conditions
* Plant genetics
* Harvesting and processing

The time at which the plant is harvested affects the level of THC. Additionally, female varieties have higher levels of THC than male varieties. As a cannabis plant matures, its chemical composition changes. During early development, cannabidiolic acid is the most prevalent chemical. Later, cannabidiolic acid is converted to cannabidiol, which is later converted to THC when the plant reaches its floral maturation.

To determine the average potency levels of marijuana, researchers need to examine a cross section of cannabis plants, which wasn't done in the 1960s and 1970s. This makes it difficult to make accurate comparisons between the THC levels of that time period and the THC levels of today.

Variations by Plant Part

The concentration of cannabinoids depends on the plant part, or more specifically, the concentration and development of resin glands to plant part. The female flower bracts have the highest concentration of resin glands and are usually the most potent plant parts. Seeds and roots have no resin glands. These shoe no more than traces of cannabinoids. Smoke seeds will give you a headache before you can get high. If you got high on seeds, then there were probably enough bracts adhering to the seeds to get you high.
Here are the potencies, in descending order, of the various plant parts:

1. Female flowering clusters. In practice you don't separate hundreds
of tiny bracts to make a joint. The whole flowering mass (seeds removed),
along with small accompanying leaves, forms the material.

2. Male flower clusters. These vary more in relative potency depending on
the strain (see "Potency by Sex," below).

3. Growing shoots. Before the plants flower, the vegetative shoots (tips)
of the main stem and branches are the most potent plant parts.

4. Leaves (a) that accompany flowers (small);
(b) along branches (medium);
(c) along main stem (large).
Generally, the smaller the leaf is, the more potent it can be.

5. Petioles (leaf stalks). Same order as leaves.

6. Stems. Same order as leaves. The smaller the stem (twig), the
higher the possible concentration of cannabinoids. Stems over 1/16"
in diameter contain only traces of cannabinoids and are not worth
smoking. The small stems that bear the flowers can be quite potent.

7. Seeds and Roots. Contain only traces (less then .01 percent) and
are not worth smoking or extracting.

This order is fairly consistent. The exceptions can be the small leaves that accompany male flowers, which are sometimes more potent than the flowers themselves. The growing shoots are sometimes more potent than the mature female flowers.
Samples of pollen show varying amounts of cannabinoids. Resin glands are found inside the anthers, alongside the developing pollen grains, and form two rows on opposite sides of each anther. Pollen grains are smaller than the heads of large resin glands ({see Plate 7}), and range from 21 to 69 micrometers in diameter. A small amount of resin contaminates the pollen when glands rupture, but most of the THC in pollen samples comes from gland heads that fall with pollen when the flowers are shaken to collect it. One study, using pollen for the sample, found concentrations of up to 0.96 percent THC, more then enough to get you high.
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