thick-walled fibres alternating with bands of thin-walled 
fibres. They have irregularly shrunken secondary walls 
(more pronounced in the thick-walled fibres) and are 
termed gelatinous (Fig. 4). Their staining reaction (note 
lighter tones in Figs. 2, 4, 6) and absence of birefringence 
under polarized light are similar to that of gelatinous 
fibres in other species that I have studied (Anderson, 
1963, 1972). 
Axial parenchyma is paratracheal. It is very scanty in 
C. indica and scanty to vasicentric in C. sativa. 
Wood rays are classed as heterogeneous I: ¢.e., both 
multiseriates and uniseriates occur, and they are com- 
posed of procumbent and erect ray cells. Those of C. 
indica are predominantly square to procumbent ; whereas 
ray cells in C. sativa are mostly erect with very few square 
or procumbent ones. The differences in cell shape are sug- 
gested in Figs. 5-6, but they are best viewed in radial 
sections. A qualitative difference in wood rays is the 
presence of numerous cuboidal or prismatic crystals of 
‘calcium oxalate in C. indica. They can be seen in all sec- 
tions under normal light but are more obvious with par- 
tial polarization of light (Fig. 5). No crystals were found 
in C. sativa ray cells (although both species have druses 
in their phloem and ground tissues). 
Discussion 
Many American botanists have thought Cannabis to 
be monotypic, possibly because only hemp, C. sativa, 
has been cultivated in this country. Most taxonomists 
who have studied the genus closely, however, recognize 
three species: C. indica Lam., C. ruderalis Janisch., and 
C. sativa L. (see Schultes et a/., 1974, for a review of the 
taxonomic history of the genus). 
Data from wood anatomy have not hitherto been uti- 
lized in the taxonomy of Cannabis. Such data might 
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