CONIFERALES (TAXACEAE) 317 



Pinaceae in this feature, which is barely represented in the latter 

 family in Juniperus and Cupressus, and in the cone scales of 

 Araucaria. 



The leaf trace is single, even the cotyledons being supplied by a 

 single vascular strand, except those of Podocarpus, in which there are 

 two entirely separate strands. In this feature Podocarpus (and 

 perhaps other podocarps) differs from the taxads and most of the 

 Pinaceae. In this case the two cotyledonary strands together form 

 one pole of the primary diarch root (141). 



The tracheids of the secondary wood are in general of the abietine- 

 ous type, the bordered pits being uniseriate; but in Saxegothaea (150) 

 the pits are flattened horizontally and occasionally tend to form two 

 ranks, and in Dacrydium the pits are two-ranked and alternate. How 

 far these araucarian tendencies will be found to prevail among the 

 podocarps remains to be seen. 



The medullary rays are simple as compared with those of Pinaceae, 

 especially the Abietineae. In Saxegothaea, for examj)le, they are one 

 cell wide and rarely more than three cells deep. Resin canals are 

 not present at all in taxads; they do not occur in the secondary wood of 

 podocarps, so far as recorded, although they are found in the cortex; 

 and they are said to be wanting in the cotyledons of all the Taxaceae. 

 Further observation of the family for this feature, especially in con- 

 nection with experimental work, will probably relate it in this regard 

 much more definitely to the Pinaceae. 



THE LEAF 



The foliage leaves of Taxaceae are in general spirally arranged 

 (opposite and decussate in Microcachrys) , and are as variable as are 

 those of Pinaceae. Among the taxads the free, bladelike needles 

 prevail; while among the podocarps there is every gradation from 

 the very small and closely overlapping and even concrescent lea^•es 

 of certain species of Dacrydium and of Microcachrys, to the large and 

 broad leaves of some species of Podocarpus (fig. 374). In Phyllo- 

 cladus there are no foliage leaves, their function being performed by 

 the phylloclads, and leaves being represented only by scales (fig. 373). 



The anatomical structure of the leaf is in general that of the leaves 

 of corresponding form among the Pinaceae (p. 237). 



