282 TRANSACTIONS OF THE [Sess. lxxxii 



This plant resembles in white flowers with dark spotting 

 N. leucantha rather than N. pardanthina, which has rose- 

 coloured flowers. It is altogether a smaller plant than 

 N. leucantha, has thicker leaves, more close-set, and with- 

 out the long delicate acuminate tips we find in N. leucantJia. 

 The flowers, too, are much smaller. Most of the specimens 

 show solitary terminal flowers, but one has a ripening ovarj- 

 of a second flower below the terminal one. 



All these plants which have been named Nomocharis are 

 without doubt rightly placed in it. Whether specific rank 

 can be maintained for all of them is a question that can 

 only be answered with certainty when we know more about 

 them. That the N. pardanthina and N. leucantha of cul- 

 tivation are difl'erent species seems to me on the evidence 

 to be unquestionable. N. ineleagrina reads also distinct. 

 N. Mairei is the doubtful species looking to N. pardanthina 

 in foliage, to N. leucantha in flower characters. It is an 

 outlier from the distribution of the other species. These 

 are Mid. Western and W.N. Western Yunnan plants. It 

 is from N.E. Yunnan, and we know that the plants 

 of this area are, as a whole, different from, if nearly 

 allied to, those of Western Yunnan. At the same time 

 we are prepared in dealing with tuber-forming plants to 

 find areas of specific distribution much wider than those 

 of other plants. Prolonged hypogaeous life removes the 

 plant — and the deeper the more effectively — from the in- 

 fluence of factors whicli act upon and bring about modi- 

 fications in forms that have prolonged epigaeous life, 

 and the greater constancy in conditions of life encourages 

 greater constancy in form. The specific isolation which is 

 so marked a phenomenon in the flora of the mountainous 

 regions of Western China — see, for example, the genera 

 Primula and Rhododendron — may quite well be less con- 

 spicuous in such a genus as Nomocharis, and the geo- 

 graphical distribution of N. Mairei cannot be regarded 

 therefore as a point of much weight in relation to the 

 question of its identity with species from farther west. 



I turn now to the question of the position of Nomocharis 

 as a genus. The leading characters of diagnosis may be 

 stated thus : — 



