S6 



■t 



eventually developing into a stem, most probably in the fol- 

 lowing year. 



There is no regularity in regard to the number of Inter- 

 nodes by which the tubers arc formed ; it seems to vary from 

 three to four. The form of the tubers is, on the contrary, 

 very uniform, cylindrical, broadest at the middle, and taper- 

 ing at both ends. They contain a large quantity of starch. 

 Fig. 127 illustrates the underground part of a very old plant, 

 and we there see that the true tuberous rhizome is wanting. 

 The whole rhizome consists merely of a stolon, which has 

 been separated from the primary rhizome, and of which the ^x. 



ascending branches proceed from small tubers, each repre- 

 senting one single internode. It denotes the fact that the lat- 

 eral branch (br-) has been developed from the axil of 

 a scale-like leaf, without being preceded by any formation 

 of tubers, while the main branches (Br^ and Br-) form 

 tubers above each leaf, which support a lateral branch. 

 Strong roots proceed from the inferior face of the tubers, while 

 the stolons otherwise are mostly destitute of roots. It is ^ 



especially the ability of forming these tubers that makes the 

 stolons able to continue their life after having been separated 

 from the main rhizome of the plant. 



I 





Hcmei'ocallis fjilva. 



This plant is not properly indigenous to America. It is 

 a native of Europe, but has been cultivated here for a long 

 period and sometimes occurs escaped from cultivation. A 

 germinating plantlet has been figured on Plate XVI, F'ig. 

 128, where we see a rather strongly developed primary root 

 (R) and one secondary root (r) which has grown out through 

 the base of the sheath that is formed by the cotyledon. The 

 cotyledon itself is partly enclosed in the seed, or at least its 

 apex is, while the base is free and forms, as mentioned above, f 



a sheath around the plumule, which has developed three 

 leaves (L^-L^); the latter are linear and carinate. The plant 

 shows the same general course of development in regard to 

 its germination as do most of the monocotyledonous plants, 

 but there is, however, quite an interesting fact, which must 



i 



