domesticated groups: the two marijuana groups and Chinesefiber plants. Additional
but less clear support for this separation was found by examination of terpene
chemistry (Hillig2004a) and cannabinoid chemistry (Hillig and Mahlberg 2004 ),
and the evidence was clearer for cultivated accessions than for ruderal ones. In these
studies Hillig assigned the Europeanfiber plants to“C. sativa,”and the three
eastern groups to“C. indica,”noting that this had the unexpected effect of com-
bining withinC. indicathe two marijuana groups and Chinese hemp. Hillig’s data
are valuable in indicating that there was probably in ancient times a genetic dif-
ferentiation trend between the plants of western Eurasia (and consequently Europe)
and those of eastern Eurasia. Likely, European hemp went through a genetic bot-
tleneck as it was being selected from the more eastern plants. However, by evo-
lutionary standards this trend seems very minor, since not a single reliable character
has been found to distinguish the western (European) and eastern kinds collectively,
nor has a combination of morphological characters been suggested that could serve
to separate them reliably, as is necessary in conventional plant taxonomic identi-
fication keys. Recent DNA evidence does indicate that at the molecular level
combined genetic loci may be usable to discriminate certain European hemp strains,
indica-type and sativa-type plants (Sawler et al. 2015 ; Lynch et al. 2015 ). The
situation is perhaps analogous to human blood group geography, thought to have
resulted from a combination of random genetic drift and selection for disease
resistance (Anstee 2010 ), and certainly not warranting formal taxonomic recogni-
tion. The information is, however, useful for tracing genetic relationships and
identifying strains and cultivars.
1.13 A Rationale for Emphasizing the Principal Selected
Character Complexes in ClassifyingCannabis
Aside from groups resulting from hybrid origin or lateral gene transfer, it is usually
assumed that organisms sharing a unique set of characteristics arose from a single
ancestor. Indeed the cladistics school of classification insists that recognized tax-
onomic groups must have a single origin, and uses a phyletic pattern of bifurcating
groups as the theoretical justification for hierarchical classification. However,
adaptive gene complexes within taxonomic groups frequently appear to have arisen
recurrently, i.e. repeatedly, independently, and in parallel (e.g. Arendt and Reznick
2007 ; Levin 2001 ). Many crops appear to have originated repeatedly and inde-
pendently within the same species (Diamond 2002 ). In the long course of history,
fiber strains ofCannabiswere probably selected independently in different geo-
graphic regions, and the same is likely true for marijuana strains, a phyletic pattern
that is not hierarchical in organization, and reflects the difficulty of classifying
variation within many species. In arguing against the application of hierarchical
classification below the species level, Jeffrey ( 1968 ) pointed out:“Similar selection
pressures, operating on genetically similar but distinct lines, may evoke similar
responses in those line, giving rise to parallel variation, the homologous series of
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