﻿194 



RELATIONSHIPS. 



order of the remnants of the leaf bases of former years is clearly to be seen. The 

 trunks of the Floridian cycads are hence, notwithstanding their subterranean habit 

 and unusual appearance, typical in every respect. The slow elimination of the old 

 leaf bases is doubtless due, in their case, to growth in a protected underground 

 position, and may hence be a trunk habit secondarily acquired. The subordinate 

 position of these, comparatively speaking, dwarf plants as underbrush in large 

 forests of pine and in the denser " hummocks" in the case of Z. pumila has, together 

 with differential climatic change, probably, therefore, resulted in the course of 



time in some diminution in size, an 

 underground habit, and nearly complete 

 removal of the armor. 



The freedom with which these trunks 

 branch is noteworthy, as recalling quite 

 exactly the numerous branches of the non- 

 columnar trunks from the Black Hills. 

 A male or female plant often gives rise 

 to a whole clump of the same sex, and 

 a series of closely-set branches has been 

 observed to bear as many as thirty-nine 

 staminate cones. This free branching, 

 which is said to be supplemented by the 

 power of new growth from " cuttings," is 

 very clearly an important means of repro- 

 duction. 



Cones. — The branching habit together 

 with the relatively large size of the cones 



"stage of growth. Slightly bifurcate trunk bearing three of both Sexes in Z. Jloridana give the 



staminate cones on the left and two on the right incipient plants a Striking appearance when ill 



branch. Trunk shown with leaves removed and as if g^ j n g g & of CQnes 



cut away on the ground-level. From Wieland (193). , 



forming a portion only of a staminate 

 clump of trunks is shown. These cones vary much in size, number of sporo- 

 phylls in the rank, and number of ranks, facts all having a bearing on the deter- 

 mination of related or otherwise analogous fossil species. 



The ovulate cones are, indeed, unusual. As is well known, among the 

 living cycads we find the largest ovules seen in the vegetable kingdom, though it is 

 surely significant that these structures are comparatively small in the Cycadeoideoe. 

 In figure 106 the curious fact is well shown that ovulate cones of Z. Jloridana, 

 even many months before the gainetophytes are fairly mature, are often distinctly 

 larger than the underground trunks which bear them. As a trunk may bear 

 several ovulate cones, this contrast in size may become even greater. Large mature 

 cones are several inches longer than the young unfertilized cones here figured. 

 As in all cases, however, where the sporophylls are closely organized into typical 

 cones, appression faces form, and to a large degree remodel and thus partially con- 

 ceal the original characters of the component parts, limiting especially the spaces 

 occupied by the ovules. These do not hence approach the immense size of those 



Fig. 107. — Zamia Floridana DC. <$. X $■ November 



