K. E. Stevois — Petrified Palms. ^^-3 



Classificatioit. 



Ill tlie present state of knowledge regarding the anat- 

 omy of fossil, and living, palms the investigator may 

 well adopt the system used by Stenzel (3) which is the 

 result of the most extensive study of the anatomy of 

 fossil palms yet published. Like all* artificial systems it 

 presents some difficulties in application. For example, 

 w^hen the writer described P. andiorus he was inclined to 

 place it in Stenzel's class C, '^Kokos-like stems," because 

 no marked difference in size, shape or arrangement of the 

 inner and outer bundles was detected. The bundles in 

 this species are, however, much too far apart to agree with 

 the "Kokos-like stems." Again, P. anchorus might w^ell 

 be placed in the subdivision Lacunosa of Stenzel's groui) 

 Complanata, which includes species with the fibrovascular 

 bundles separated from one another by more than one 

 diameter. But so doing involves the assumption that in 

 the extreme outer portion of the stem, lacking in the 

 specimen, the fibrovascular bundles were close together, 

 this being a distinguishing character of Stenzel's Class B. 

 ^ ' Corypha-like stems. ' ' 



The two species considered here fit easily into Stenzel's 

 scheme. In P. cheyennense both peripheral and more 

 central bundles have the sclerenchyma portion much 

 larger than the vascular portion, which together with the 

 fact that the central bundles are more widely separated 

 than the peripheral places it among the ' ' CoryphaJike 

 stems." The shape of the sclerenchyma portion, which 

 is flattened where it joins the vascular portion, places it 

 in Group IV, '^ Complanata, " and the close arrangement 

 of its fibrovascular bundles and its dense fundamental 

 tissue indicate that it belongs to the sub-group '* Solida." 



P. cannoni also apparently belongs to the group ' ' Com- 

 planata" but to the sub-group "Lacunosa" because the 

 fibrovascular bundles are more than one diameter apart, 

 and the fundamental tissue has large intercellular spaces. 

 Among species belonging to this sub-group it most nearly 

 resembles P. remotum in the arrangement of its fibrovas- 

 cular bundles and in the presence of thick w^alled cells 

 scattered among the cells of the fundamental tissue. The 

 vascular portion of the bundle in P. remotum is, however, 

 much larger as compared to the sclerenchyma portion, 

 than in P. cannom. 



Bureau of Plant Industry, 

 Washington, D, G. 



