346 



THE ANATOMY OF WOODY PLANTS 



numerous, and bars of Sanio are clearly developed. The state- 

 ment is often made that the ligneous structure of the Taxineae 

 is free from parenchymatous elements (Fig. 252). This is certainly 

 true of the mature wood of the stem in both Taxus and Torreya. 

 If, however, the roots in the two genera be examined, a varying 

 amount of storage parenchyma is discovered which is ordinarily 

 better developed in proximity to the region of the primary wood 

 (Fig. 253). In species common to Europe and America, namely, 



Taxus baccata and its vari- 

 eties, very little paren- 

 chyma is found even in the 

 root; but in oriental species 

 of the genus storage ele- 

 ments are somewhat abun- 

 dant in this organ. The 

 young stem, and particu- 

 larly the root, of the genus 

 Torreya show clearly 

 developed longitudinal 

 parenchyma in the wood. 

 In CephalotaxuSy which by 

 reason of the presence of a 

 well-developed female cone 

 at an early stage must be 

 regarded as a primitive genus of the subtribe, parenchyma is 

 markedly abundant in the organization of the wood. Injuries, 

 also, frequently result in the recall of parenchyma in those taxineous 

 woods which are normally without it. The generally uniseriate 

 rays of the subtribe do not show the presence of traumatic ray- 

 tracheids as a result of injury, and in this respect they present a 

 marked resemblance to the woods of the Podocarpineae. Resin 

 canals are conspicuously absent in the ligneous structures of the 

 Taxineae, and not the slightest evidence of their former occurrence 

 can be produced by experimental data. The genus Taxus is 

 entirely without resin canals, even in its leaves, thus providing 

 the only example of a conifer completely lacking these structures. 

 An interesting parallel is presented by the hemlock (Tsuga) among 



FIG. 252. Transverse section of the wood 

 of the stem in Taxus cuspidata. 



