83 



flowers the same year. The base of two other stems are to 

 be seen at 2 and 3, indicating their rank in regard to their 

 time of development, No. 3 being the older one, and these 

 stems carried several leaves which had persisted over winter. 

 The three other basal parts (Nos. 4, 5 and 6) were the 

 only remaining parts of old faded stems, and the probable 

 age of the whole plant was at least six years. Only one stem 

 had been developed each year in this specimen, but the period 

 necessary for the formation of tlic tubers (say, for instance, the 

 younger one, which was relatively longer than the other 

 ^ ones and was covered with about three scale-like leaves) is 



uncertain. 



As regards the foliage of S. 7'otundifolia, as already re- 

 marked above, there seems as if there Avere quite a consider- 

 able variation even in the same specimen. The form, indi- 

 cated as typical for this species, should be, according to De 

 Candolle (1. c), '' limbi ovati vel ovales, basi subcordati, 

 obtusi vel prope petiolum cuneati, apice (in eodem ramo) 

 .^ s^pius acute cuspidati vel acuminati, et interdum obtusi," 



The most characteristic feature of the leaf, when the question 



is to distinguish it from other species, for instance, 5. glauca, 



with which the young specimens showed a great resemblance, 



is the minutely dentate margin. As regards this character it 



accords, however, with S.hispida, Muhl., but the leaves of this 



species show from seven to nine nerves, whereas there are 



, not more than five to seven in S, rotniidifolia. The consist- 



I ency of the leaf is also different, as the leaves of ^. rotundi- 



1^ folia are thick, almost coriaceous, in contrast to the leaves in 



5. hispida. 



w 



We will shortly consider the leaves of S. rotaudifolia, 

 figured on Plate XV, which have been taken from a full- 

 grown plant, or from v^ery young specimens, the ages o{ which 

 were only one year. 



The leaf in Fig, 121 shows the typical form, while the 

 other one (Fig. 122), which has also been taken from an older 

 plant, is more elongated and tapers gradually to the pointed 

 apex. We find this form again in Fig. 113, which shows the 

 youngest leaf of a one-year-old plant. Tn I-'ig. 114 we see 



