The physical and chemical features of Cannabis plants grown in the United Kingdom of Great Britain and Northern Ireland from seeds of known origin - Part III: third and fourth generation studies

Sections

ABSTRACT
Introduction
Experimental
Results and discussion
Conclusions

Details

Author: B. J. TAYLOR, J. D. NEAL, T. A. GOUGH
Pages: 75 to 81
Creation Date: 1985/01/01

The physical and chemical features of Cannabis * plants grown in the United Kingdom of Great Britain and Northern Ireland from seeds of known origin - Part III: third and fourth generation studies

B. J. TAYLOR
J. D. NEAL
T. A. GOUGH
Laboratory of the Government Chemist, Cornwall House, London, United Kingdom of Great Britain and Northern Ireland

ABSTRACT

Two further generations of Cannabis plants have been grown from seeds produced by earlier generation plants which were raised in the United Kingdom of Great Britain and Northern Ireland in 1980 and 1981. The original seedstocks were from known countries of origin. Although there are exceptions, both the physical and chemical characteristics of the third and fourth generation plants generally resemble those of their parents. The yields of cannabis vary substantially from year to year. The total tetrahydrocannabinol contents also vary, but are comparable with the levels in the original plants. Tetrahydrocannabinolic acid continues to predominate over free tetrahydrocannabinol and is much higher than in the original plants.

Introduction

Information about the physical and chemical features of cannabis is of considerable forensic importance to determine whether an amount of cannabis seized in the illicit traffic originated in the United Kingdom or was smuggled into the country. If such information about a sample of unknown origin is compared with that of samples of known origin, an opinion as to the geographical origin of the unknown sample can be formed.

This article summarizes data obtained in a multi-generation study that has monitored the physical and chemical characteristics of Cannabis grown in the United Kingdom from seedstock of known foreign origin. Previous work [ 1] [ 2] showed that changes in successive generations occurred mostly in the chemical rather than physical characteristics of the plants. In most instances there was a strong morphological similarity between the offspring and their parents and grandparents. Further studies of generations have been carried out and data on the 1982 and 1983 growing seasons representing the third and fourth generation of the plants are presented in this article.

* The term Cannabis in this article refers to Cannabis sativa L., and the term cannabis refers to marijuana.

Experimental

This study deals with the plants that were grown under the same conditions and at the same location as previously described [ 1] [ 2] . The plants used for pollination of the 1981 and 1982 crops to provide seeds for 1982 and 1983 respectively were, where possible, chosen to reflect the strongest characteristics in plants from the originating country. The plant reference numbers are listed in table 1.

Table 1

Selection of Cannabis plants for pollination to provide seeds for planting in the subsequent year

 

1981

1982

Country of origin

Male plants

Female plants

Male plants

Female plants

Morocco
1.3 1.2 1.2.5 1.2.3
Sri Lanka
1.2 1.1 1.2.5 1.2.8
Zambia
1.1 3.1 3.1.6 3.1.7

Note: The digits refer to the plant number in each successive year in a given lineage.

For Morocco the plants selected were low in tetrahydrocannabivarin (THV) for both 1981 and 1982. In 1981 neither the male nor female plants contained cannabidiol (CBD), while in 1982 the female plants only contained CBD. Plants grown in Morocco are usually low in THV, but have readily detectable quantities of CBD. This has not been the case with most of the plants grown in the United Kingdom from Moroccan seedstock.

For Sri Lanka, the plants selected for both 1981 and 1982 all contained CBD and low levels of THV.

For Zambia, the plants selected for 1981 and 1982 contained no CBD, but all had high levels of THV.

The study of plants from seedstock from Zimbabwe was not pursued, as the characteristics of these plants in the earlier studies were similar to those from Zambia. The study of plants from seedstocks from Thailand was abandoned as the 1981 crop did not produce any male plants.

The 1982 and 1983 plants were harvested at maturity with the exception of the three plants from Zambia in 1982, which showed no sign of flowering. In 1982, as in previous years, the plants from Morocco matured first followed by plants from Sri Lanka and Zambia. The males generally flowered first. In 1983, the plants from Sri Lanka and Zambia matured much earlier than in previous years. In physical appearance, all plants resembled their parents. Climatic conditions for June, July and August of 1982, with 516.7 hours of sunshine and a mean temperature of 18.2oC, were very similar to those previously reported. The year 1983 was exceptional, with 664.9 hours of sunshine and a mean temperature of 19.4o C. *

After harvesting and air drying, the larger stalks and stems were removed and the remainder weighed. Samples of cannabis from each plant were chopped and mixed to give a homogeneous material prior to analysis by thin layer chromatography (TLC) [ 3] , gas liquid chromatography (GLC) [ 4] and high performance liquid chromatography (HPLC) [ 5] . The analyses were carried out within one month of harvesting. The results are given in table 2 for the 1982 crop and table 3 for 1983.

According to data from the Meteorological Office, Bracknell, Berkshire, United Kingdom.

Table 2

Data on Cannabis plants grown in 1982

 

Content (percentage by weight)

 

Plant number a

Harvest date

Sex

Weight of cannabis (grams)

CBD b

THC b

THV b

THCA

THC

CBCh

Ratio of THCA to THC

Ratio of CBD b to THC b

Morocco
                     
1.2.1
July
M
17
ND
1.10
c
0.88 0.33
P
3
-
1.2.2
August
F
31
ND
2.20
-
1.90 0.50
ND
4
-
1.2.3
August
F
23 1.3 0.88
-
0.80 0.18
ND
4 1.5
1.2.4
August
F
30
ND
0.55 1.1 0.57 0.05
ND
11
-
1.2.5
July
M
18
ND
0.90 1.4 0.88 0.13
P
7
-
1.2.6
August
F
22
ND
1.80 0.9 1.90 0.11
ND
17
-
1.2.7
August
M
8
ND
0.59
-
0.40 0.24
P
2
-
1.2.8
August
F
24
ND
0.99 1.4 1.00 0.09
ND
11
-
Sri Lanka
                     
1.1.1
August
F
48 2.2 1.50
-
1.50 0.20
ND
7 1.5
1.1.2
August
F
36 1.9
0.18 d
-
0.13 0.07
ND
2 11
1.2.3
August
F
43
ND
2.90
-
3.00 0.27
ND
11 0
1.2.4
August
F
44 1.4 0.63 0.6 0.59 0.11
ND
5 2.2
1.2.5
August
M
36 2.9 1.50
-
1.50 0.22
ND
7 1.9
1.2.6
August
M/F
27 2.7 1.50
-
1.50 0.16
ND
9 1.8
1.2.7
August
M
37
ND
2.30
-
1.90 0.61
P
3 0
1.2.8
August
F
55 2.1 1.10
-
1.00 0.21
ND
5 1.9
Zambia
                     
3.1.1
October
I
16
ND
1.60 2.5 1.8 0.08
ND
23
-
3.1.2
October
M
13
ND
1.30 2.3 1.4 0.08
ND
18
-
3.1.3
October
I
16
ND
1.70 2.3 1.9 0.08
ND
24
-
3.1.4
October
I
14
ND
3.90 2.7 4.4 0.08
NDS
55
-
3.1.5
September
F
20
ND
1.60 2.1 1.7 0.08
ND
21
-
3.1.6
September
M
34
ND
0.30 1.9 0.3 0.08
ND
4
-
3.1.7
September
F
53
ND
1.20 1.8 1.3 0.08
ND
16
-
3.1.8
October
F
36
ND
0.90 1.9 1.0 0.08
ND
13
-

Note: F = female plant, I = immature plant, M = male plant, ND = not detected (limit of detection 0.05 per cent), P = present (less than 0.2 per cent), but not quantified.

aThe digits refer to the plant number in each successive year in a given lineage.

bAs determined by GLC (i. e. includes decarboxylated acid).

cWhere no value is quoted the THV is smaller than THC.

dThis was an exceptionally low value.

Table 3

Data on Cannabis plants grown in 1983

 

Content (percentage by weight)

 

Plant number a

Harvest date

Sex

Weight of cannabis (grams)

CBD b

THC b

THV b

THCA

THC

CBCh

Ratio of THCA to THC

Ratio of CBD b to THC b

Morocco
                     
1.2.3.1
August
F
46 0.9 0.68
ND
0.62 0.14
P
4 1.3
1.2.3.2
August
F
23
ND
1.20 0.13 1.16 0.18 0.2 6 0.2
1.2.3.3
August
M
42 1.6 0.81 0.10 0.79 0.12
P
7 2.0
1.2.3.4
August
F
46 1.4 0.95
ND
0.87 0.19
P
5 1.6
1.2.3.5
August
F
57 1.1 0.80
ND
0.75 0.14
P
5 1.4
1.2.3.6
August
F
49 1.0 0.63
ND
0.50 0.19
P
3 1.6
1.2.3.7
August
F
62 0.8 0.69
ND
0.60 0.16
P
4 1.2
1.2.3.8
August
M
80
ND
1.70 1.2 1.73 0.18 0.4 10 0.2
Sri Lanka
                     
1.2.8.1
July
M
24
ND
3.95 0.18 3.70 0.71 0.5 5 0.1
1.2.8.2
August
F
29 2.7 1.83 0.05 1.84 0.22
P
8 1.5
1.2.8.3
August
F
28 2.9 2.15 0.09 2.17 0.25
P
9 1.3
1.2.8.4
June
M
27
ND
2.40 0.08 2.13 0.53 0.3 4 0.1
1.2.8.5
August
F
35 2.0 1.55 0.06 1.50 0.23
P
7 1.3
1.2.8.6
August
F
27 1.7 1.77 0.05 1.77 0.22
P
8 1.0
1.2.8.7
August
F
23 2.1 1.40 0.08 1.37 0.20
P
7 1.5
1.2.8.8
June
M
35
ND
2.16 0.06 1.84 0.55 0.5 3 0.2
Zambia
                     
3.1.7.1
August
M
53
ND
1.60 0.2 1.63 0.13 0.17 12 0.11
3.1.7.2
August
F
73
ND
1.40 0.5 0.99 0.53 0.17 2 0.12
3.1.7.3
August
M/F
67
ND
0.56 1.1 0.52 0.10
ND
5 0.11
3.1.7.4
June
M
43
ND
1.40 0.5 1.25 0.30 0.23 4 0.16
3.1.7.5
July
M
37
ND
0.72 1.1 0.54 0.25 0.14 2 0.19
3.1.7.6
June
M
49
ND
1.10 0.4 1.07 0.16 0.15 7 0.14
3.1.7.7
July
M
39
ND
1.06 0.4 0.73 0.42 0.31 2 0.29
3.1.7.8
August
F
55
ND
1.40 0.7 1.44 0.14 0.17 10 0.12

Note: F = female plant, I = immature plant, M = male plant, ND = not detected (limit of detection 0.05 per cent), P = present (less than 0.2 per cent), but not quantified.

aThe digits refer to the plant number in each successive year in a given lineage.

bAs determined by GLC (i. e. includes decarboxylated acid).

Results and discussion

As in previous years, the cannabis prepared from the 1982 and 1983 crops was green or yellow-green, friable material. In most cases the cannabinoid pattern, as shown by TLC, was similar to that of the parent.

All plants originating from Zambia, as in previous years, had a higher level of THV than tetrahydrocannabinol (THC). The actual levels of THV were much lower in 1983 than in previous years. Appreciable levels of THV also occurred in half of the plants originating from Morocco and one of the plants originating from Sri Lanka, both for the first time in 1982. In 1983, all the plants originating from Sri Lanka contained THV.

The majority of the plants originating from Sri Lanka continued to contain CBD. In common with the 1981 crop, only one plant of Moroccan origin was found to contain CBD in 1982, but in 1983 six contained CBD. Four of the 1982 plants originating from Morocco contained high levels of cannabichromene (CBCh), whereas none contained CBD. In 1983, the two plants with the highest levels of CBCh were the only ones that did not contain CBD. This is in agreement with observations by Fairbairn and Rowan [ 6] .

The THC content of the plants originating from any of the three countries continued to be lower than in the original plants. Total THC values, including THC and tetrahydrocannabinolic acid (THCA), were similar to the values in the original plants, except for Sri Lankan plants in 1983, when the values were much higher (see table 4). One out of eight plants originating from Sri Lanka was exceptionally low in total THC in 1982. Ratios of the concentrations of THCA to THC are given in table 5 for all generations.

Table 4

Mean values of total THC content

Country of origin

Seedstock

1980

1981

1982

1983

Morocco
1.5 3.0 0.67 1.1 0.9
Sri Lanka
1.0 1.1 0.80 1.5 2.2
Zambia
1.5 0.84 0.73 1.6 1.2

Table 5

Mean values of THCA/THC ratios

Country of origin

Seedstock

1980

1981

1982

1983

Morocco
3.1 12 2.2 7.4 5.5
Sri Lanka
1.7 14 8.3 6.0 6.3
Zambia
1.2 83 9.0 22 5.5

The majority of the other cannabinoids studied were also present to a greater extent as acids. Mean values for the yields of cannabis for each year are given in table 6. For all countries, the female plants generally continued to give a greater yield than the corresponding male plants.

Table 6

Mean yields of Cannabis plant

 

1980

1981

1982

1983

Country of origin

Mean

sd

Mean

sd

Mean

sd

Mean

sd

Morocco
44 26 50 26 21 7 51 17
Sri Lanka
46 6.2 104 46 41 8 29 4.5
Zambia
25 3.4 46 16 25 13 52 13
Mean
38   66   29   44  

Note: sd = standard deviation.

Conclusions

All the plants physically resemble each other and are typical in appearance to Cannabis grown in the United Kingdom. However, in most instances the cannabinoid distribution was still typical of the source countries.

References

001

P. B. Baker, T. A. Gough and B. J. Taylor, "The physical and chemical features of Cannabis plants grown in the United Kingdom of Great Britain and Northern Ireland from seeds of known origin", Bulletin on Narcotics (United Nations publication), vol. 34, No. 1 (1982), pp. 27 - 36.

002

P. B. Baker, T. A. Gough and B. J. Taylor, "The physical and chemical features of Cannabis plants grown in the United Kingdom of Great Britain and Northern Ireland from seeds of known origin - Part II: second generation studies", Bulletin on Narcotics (United Nations publication), vol. 35, No. 1 (1983), pp. 51 - 62.

003

R. Fowler, R. A. Gilhooley and P. B. Baker, "Thin layer chromatography of cannabinoids", Journal of Chromatography, vol. 171, 1979, pp. 509 - 511.

004

P. B. Baker, K. R. Bagon and T. A. Gough, "Variation in the THC content in illicitly imported Cannabis products", Bulletin on Narcotics (United Nations publication), vol. 32, No. 4 (1980), pp. 47 - 54.

005

P. B. Baker and others, "Determination of the distribution of cannabinoids in cannabis resin using high performance liquid chromatography", Journal of Analytical Toxicology, vol. 4, 1980, pp. 145 - 152.

006

J. W. Fairbairn and M. G. Rowan, "Cannabinoid patterns in Cannabis sativa L, as an indication of chemical race", Journal of Pharmacy and Pharmacology, vol. 27, 1975, p. 90P.