Date: Mon, 1 Aug 94 19:07:22 EDT
From: andy@eng.tridom.com (Andrew P. Klenzak)

Last week (Jul 27 1994) litch@bga.com (R. Michael Litchfield) wrote:
>In article ,
>Andrew P. Klenzak  wrote:
>>The leaves of a Cannabis plant can be nearly as potent as the growing
>>shoots and/or buds.
>
>Not really, there is a trace amount of THC in the leaves but 95% of the THC
>is in the bud and the leafnode immediatly down from it. There was a study
>this done by the university of Illinois I believe (do a keyword search
>on the ag abstracts to find it).
>
>>Andy
>
>-michael
	
I'd be interested in the specifics of that study you remember reading
about, as well as a full reference citation.  I looked into it and
came across one article/paper that dealt with the potency of the 
various parts of the Cannabis plant.  I didn't/don't have access
to medline, so I wasn't able to that thorough of a search.

The following is from _The cannabinoid content of Cannabis sativa L.
grown in England_ by Fairbairn and Liebmann in the Journal of Pharmacy 
and Pharmacology, vol 26 (Dec. 1974), pp. 413-419.  This work is
cited in at least two growing books I know of.

The leaves referred to by the chart are "healthy leaves from plants at
vegetative or flowering stages and which were not closely associated
with a floral axis."  They are *not* vegetative tops (growing shoots)
or flowering tops (buds), as those are two separate, distinct
catagories that the researchers differentiate.

Table 3.
THC content (% of air dried material) and air-dry weight of leaves
collected simultaneously at different positions on the plant.

                         plant 1        plant 2        plant 3
Position on plant         (SP5)          (SP5)        (UNC 335)
~~~~~~~~~~~~~~~~~        ~~~~~~~        ~~~~~~~        ~~~~~~~~
TOP        % THC           6.1            6.9             4.8
          dry wt (mg)      35             21              28
MIDDLE     % THC           3.0            5.5             3.1
          dry wt (mg)     119             74              70
BOTTOM     % THC           0.8            4.0             1.5
          dry wt (mg)     314            133             133

[top:mid:bot ratios       8:4:1        1.7:1.4:1         3:2:1

The article also discusses (and shows) the large variability between
plants of the same variety -- Table 2 shows how one plant (UNC 255)
can have 3 times the %THC as another of the same variety.  It also 
notes that most plants (not all) will tend to have high ratios when
comparing the potency from the top to the bottom.  But as plant 2
of the SP5 variety shows, it can be nearly uniform.

Now, given that one can easily get high on 1% THC material (be it
buds or leaves), it would seem to make sense to keep/smoke/extract
the leaves.  Hell, the topmost leaves examined in this study have
a greater % THC than a great deal of "ditchweed" out there!

Now, you'd thought that 95% of the THC was in the buds.  This
*may* actually be true -- it all depends on the total weight of
the buds compared to that of the leaves.  If you get 10 oz. of (dried)
buds from a plant and 0.5 oz. of dried leaves, then yes, 95% of the
THC may be in the buds, but that 5% in the leaves is *still* very
adequate to get you high.

Sure, only the topmost leaves on some plants will be worth your while.
The point is you should always test some of the leaves to see how
potent they are -- throwing away material with >= 3% THC is ludicrous!

Andy


From: DrewH37597@aol.com
Message-Id: <9408092314.tn875436@aol.com>
To: drctalk-l@netcom.com
Date: Tue, 09 Aug 94 23:14:50 EDT
Subject: NIDA Potency Tables, Marijuana

	Marijuana Potency Monitoring Project, Report #50
	        April 1, 1994 through June 30, 1994

Page 3, Table 1. 
Normalized Versus non-normalized Cannabinoid 
Averages of Illicit Cannabis Samples by Year Seized

NORMALIZED
 Year    Seizures   THC   CBD   CBC    CBN  Kilograms
                  #           %       %        %         %         Total
(rounded)
1974       113        0.36     0.00      0.08       0.44        18013
1975       150        0.48     0.00      0.09       1.17        67160
1976       210        0.98     0.00      0.12       0.62      101192
1977       251        1.76     0.00      0.10       0.74      173612
1978       132        1.72     0.01      0.12       1.27      154533
1979       221        1.53     0.02      0.12       1.40        71860
1980       153        1.96     0.01      0.16       0.69        44095
1981       260        2.11     0.02      0.18       0.98      147440
1982       487        3.34     0.11      0.17       0.74      299892
1983     1229        3.44     0.02      0.16       0.54      776566
1984     1119        3.96     0.07      0.13       0.47    1259065
1985     1653        2.63     0.14      0.09       0.52      729213
1986     1554        2.24     0.06      0.11       0.44      669472
1987     1699        2.23     0.23      0.11       0.33      621069
1988     1822        3.84     0.18      0.14       0.54      352194
1989     1272        2.66     0.20      0.16       0.60      179103
1990     1260        3.83     0.11      0.18       0.37        52987
1991     2505        3.78     0.17      0.17       0.27        76278
1992     3539        1.96     1.21      0.09       0.23      698443
1993     3229        3.89     0.41      0.16       0.32      378383
1994*      343*      4.57     0.23      0.23       0.54        44461*
* Through June 30

NON- NORMALIZED
Year       THC   CBD   CBC    CBN  
                %       %        %         %  
1974        0.89    0.03     0.08      0.49
1975        0.71    0.03     0.10      0.55
1976        0.72    0.00     0.09      0.37
1977        0.91    0.08     0.10      0.43
1978        1.37    0.01     0.12      0.67
1979        1.67    0.02     0.12      0.24
1980        2.06    0.10     0.14      0.47
1981        2.28    0.35     0.16      0.38
1982        3.05    0.34     0.19      0.33
1983        3.23    0.22     0.16      0.30
1984        3.29    0.24     0.17      0.34
1985        2.82    0.28     0.14      0.23
1986        2.30    0.29     0.15      0.21
1987        2.93    0.30     0.17      0.30 
1988        3.29    0.28     0.15      0.30
1989        3.06    0.37     0.14      0.22
1990        3.36    0.38     0.18      0.19
1991        3.00    0.45     0.19      0.16
1992        3.10    0.24     0.20      0.36
1993        3.32    0.39     0.19      0.28 
1994*       4.45    0.40     0.21      0.33
Through June 30, 1994


These are the main tables, more to follow.  NIDA took about two months give
or take to respond to my request...

Drew