T. Holm — Cliionophila Benth. 33 



the rhizome representing a sympodinm, while the aerial 

 stem is a true monopodium. Unfortunately the literature 

 gives little information about these structures, and with 

 regard to the structure of the shoot above ground being a 

 monopodium so distinctly represented by Chionophila, 

 there is no mention of this structure being represented by 

 any of the other Scrophulariaceae ; as a matter of fact the 

 word '^monopodium" does not occur in any of the Ameri- 

 can manuals of Botany, dealing with floras of certain 

 regions. Nevertheless it constitutes a character of no 

 small importance, and none of the species of Pentstemon, 

 which I have examined, exhibit this structure. It may be 

 mentioned at the same time, that Arabis dentata exhibits 

 a monopodium exactly as that of Chionophila, and is the 

 only Arabis, known so far, of which the shoot is of mono- 

 podial grow^th. The monopodium occurs also in Clay- 

 tonia, Calandrinia, Viola etc., which I have described in 

 previously published papers on these genera. 



Concerning the inflorescence in Chionophila, this is not 

 a spike, but a unilateral cyme, a monochasium ; the floral 

 stem begins with two or three pairs of small, linear, oppo- 

 site bracts without buds ; but above these the bracts be- 

 come somewhat larger, broader, and we find at each pair 

 a single flower, and a lateral branch, which again termi- 

 nates in a flower with two bracts and a lateral branch and 

 so on. In Chionophila the composition of the inflorescence 

 is not so very distinct on account of the short internodes, 

 the leaves and flowers being rather crpwded, but in Col- 

 linsia grandiflora Dougl. the structure is plainly visible, 

 and corresponds exactly with, that of Chionophila. In 

 Pentstemon, on the other hand, there is a regular cyme in 

 the axil of each leaf; in P. Newberryi Gr. the axillary 

 cymes are one-floAvered, there being only a single flower, 

 but with two bracts, indicating a ''dichasium" with two 

 lateral branches suppressed, non-developed. 



Characteristic of Chionophila, when compared with 

 Pentstemon, is thus the monopodial ramification of the 

 shoot, and the inflorescence representing a monochasium. 

 The floral structure has been described very exactly by 

 Gray, Bentham and Hooker, except that it seems to have 

 been overlooked, that the calyx, in fresh specimens, is dis- 

 tinctly folded lengthwise as shown in figure 2. 



Internal structure of the vegetative organs. 



The roots: — In Solereder's treatment of the Scrophu- 



Am. Jour. Sci.— Fifth Series, Vol. I. No. 1.— January, 1921. 

 3 



