possibly even more—species is still open to question, as is 
the correct nomenclature of thespecific conceptsinvolved, 
But in the basic question of whether Cannabis be 
monotypic or polytypic, we have little hesitation with 
the evidence available at this point in accepting the poly- 
typic concept. 
Central Asia and adjacent regions to the south and 
west comprise a vast area which includes a great diversity 
of geographical zones and ecological situations. It is here 
that Cannabis is commonly believed to have originated, 
although it may be difficult to pinpoint any specific area 
of origin or to determine how great the geographical 
distribution of wild hemp was before the advent of man 
(5, 29, 31). In such a region, there could easily have 
arisen divergent populations sufficiently distinct both 
morphologically and ecologically, to be considered spe- 
cies, subspecies and varieties. 
When man began to domesticate one or more of these 
species of Cannabis and carry them from place to place, 
hybridization occurred between the wild species and the 
incipient cultigens. 
Through continual introgressive hybridization with 
cultivated hemp, some of the original wild species of 
Cannabis may have gradually become extinct. This 
process increased the variability in the gene pool of the 
cultivated plants and must have imparted to them some 
of the unique characters of the wild species. This belief 
is given credence by the fact that we find great morpho- 
logical variation between populations of cultivated hemp 
in various parts of Eurasia in characters which have not 
been selected for by man, such as leaf size and shape and 
pigmentation of stem and fruit. 
Studies in the reproductive biology of different strains 
of cultivated Cannabis indicate that these plants are fully 
interfertile (17, 22). This does not mean, however, that 
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