What is the difference between Skunk and ordinary cannabis?

The variety of cannabis known as "Skunk" has attracted much publicity. Much of this publicity is inaccurate, describing the strain as a "superweed" and even implying it is a new drug entirely. Skunk is simply a variety of herbal cannabis developed for indoor cultivation, producing a bushy indica/sativa plant with early flower development and a pungent aroma. The indica type of plant does not produce as much vegetative growth as sativa varieties, and would not be expected, even in ideal outdoor conditions, to grow to a height much over 5 to 6 feet.

An objective measure of the difference between Indica and Sativa plants is internodal length, or the distance between successive branches on the main stem. Sativa cultivars (e.g. Haze, Thai) tend to have long internodes of 7-15cm, whereas Indica cultivars (e.g. Northern Lights) tend to have shorter internodes of 1-6cm. Obviously, the shorter the nodes, the greater the number of budding sites per foot height, and the higher the yield.

Although it is claimed that Skunk is many times more potent than other varieties, there is little evidence to substantiate these claims. Potencies of fresh manicured buds grown hydroponically typically range from 6% to 15%, very occasionally as high as 20% (in organic compost-based media). These are higher than imported cannabis largely because the imported material has been pollinated and produced seed, harvested, dried (usually in the sun), compressed into blocks and transported over long distances, thus by the time it is intercepted by police or customs and subsequently analysed imported material may be several months old, and often partially decomposed (if damp), resulting in a reduced THC content. By contrast, home grown sinsemilla 'buds' are frequently analysed within a few days of harvest with virtually no time for THC degradation.

Herbal cannabis cultivated indoors or outdoors may be fraudulently sold as "skunk" even though its parentage is suspect. The term has largely ceased to be used exclusively as a "trade mark", and become a generic term for herbal cannabis sold in complete flower heads, or "buds", much as "Sensi" became a generic term for herbal cannabis in the 1980s. Use of the term "Skunk" to describe any cannabis grown indoors under lights is misleading, as leaf material is of much lower potency, and is commonly thrown or given away.

It is not possible positively to identify any cannabis as the specific variety "Skunk" through using conventional forensic methods, unless genetic fingerprinting were to be used to compare with plants of known parentage. A high proportion of THC in the dried flower heads may provide circumstantial supporting evidence, although several varieties of cannabis, given the right environmental conditions, can produce potent flowering heads.

A test of the cannabinoid profile using high pressure liquid chromatography may produce evidence as to the origin of a plant, when compared to a database of profiles from plants of different origin. However, to demonstrate parentage persuasively it is necessary to compare with a plant of known (i.e. positively identified) parentage, and also to disclose all non-matching cannabinoid profiles which may have been attributed to plants of the same alleged origin, to ensure that not only do profiles match, but that they are specific to a certain variety. Different growing conditions and variation within strains can produce variations within the cannabinoid profiles of plants of the same variety.

How potent is Cannabis in the UK?

Herbal Cannabis

There are many published studies of the potency of cannabis and cannabis resin, dating back several years. Potency can be crudely expressed as the overall THC content of a sample by weight.

In evidence to the Lords Committee, Leslie King of the Forensic Science Service provided a graph showing the distribution of potencies of herbal cannabis samples ("compressed" and "hydroponic") analysed by the Forensic Science Service between 1996 & 1998. These data only relect those few cases (less than 1% of seizures) for which quantitative THC analyses were requested, and the results are reproduced in the table below.

THC content of Herbal Cannabis (King 1998)
Potency	Number of samples
range	"Hydroponic"	"Compressed"
0-2	1	14
2-4	9	13
4-6	8	5
6-8	14	5
8-10	16	5
10-12	9	2
12-14	9	0
14-16	12	0
16-18	5	0
18-20	3	0
20-22	1	0
Total samples	87	44
Average potency	9.99%	4.09%

 

Herbal cannabis with high potency (i.e. over 10%) has been seized in the UK from a variety of geographical origins over the past 20 years. Gough reported cannabis bush from India up to 12% (1979-81), Jamaica up to 13% (1984), Thailand up to 17% (1975/6), and Zimbabwe up to 12% 1978).

 

Cannabis resin (Hashish)

Cannabis resin with high potency has also been seized in the UK for many years, THC values were reported from Lebanon up to 18% (1984), Morocco up to 26% (1984), Pakistan up to 16% (1979) and India up to 26% (1978). Five seizures of Nepali hashish averaged 12% over a 5 year period (1976-80), and overall cannabis resin seizures averaged 11% in 1981 and 1984.

By contrast, most "soap bar" contains between 3% and 7% THC, although adulterated "Formula" has been known to contain as little as 0.5%. Samples of Asian "Black" resin commonly contain "Caryophyline" a constituent of clove oil, used in the perfume industry.

Occasionally, samples of more exotic resin varieties are analysed. In IDMU cases, potencies of exotic resins have varied from 7-8% (hand-pressed Moroccan), 10-11% (Nepalese blocks), and 10-12% (hand-pressed Minali cylinders/discs). One sample identified as Lebanese contained under 1% THC, although this identification is not confirmed.

The most potent resin sample found to date was 59% THC, home-made from sieving the small leaves from around the buds of exceptional plants of 20-22% THC. This resin had a soft waxy texture and looked like sugar crystals under the microscope. The forensic scientist was so surprised by the result that she ran the analysis twice to make sure!

Types of Cannabis