8i 



was collected in the larcre Smilax thickets which so com- 



t> 



monly occur in open places in the woods along the shore of 

 the Potomac, and in spite of the great similarity that exists 

 between several of the woody species of Smilax when youni^. 

 these plants showed a few characters which were sufficient to 

 distinguish them as belonging to the species '* 5. rotuiidi- 

 foliar 



In regard to the structure of the rhizome of the whole 

 genus Smilax, it is remarkable to see how few observations 

 have been made, and, with the exception of the two species, 

 S, Pseiido-cliina, L. and 5. hispida, Muhl., none of the other 

 North American representatives have been examined with 

 reference to their rhizomes. Another fact is, that there seems 

 to be a certain kind of variation in the young foliage of this 

 species, which it might not be superfluous to describe in con- 

 nection with the germination and the structure of the 

 rhizome. 



to the examination of our species 5. rotiindlfolia, 

 the seed germinates deep in the ground for a long time with 

 the fruit attached, Plate XV (Fig. 105). There is a distinct, 

 sheathing cotyledon, as shown in Fig. 106, where the upper 

 part of the cotyledon has been removed from the albumen in 

 which it was closely imbedded. Besides this enclosed part 

 there is to be observed a free one, which is the base, and 

 which forms a sheath around the plumule. 



There is also a hypocotyl (c in Figs. 105-107) more or 

 less developed, but never wanting, as it seems, according to 

 the numerous seedlings which were examined. The primary 

 root is rather slender, branched at an early stage, and persists 

 for at least the first year. The_ plumule, after having penetrated 

 the cotyledonar sheath, develops an ascending stem, the first 

 one to three leaves of which are under ground, scale-like and 



t> 



partly sheathing. After these leav^es the normal ones appear, 

 and diverge more or less from the. typical shape, which 

 has been described as ** ovate, or round-ovate, and slightly 

 heart-shaped " for this species. 



These are the general features of the germinating plantle't, 

 and we shall now see how the rhizome commences to develop. 



