140 T. Holm — Isqpyrum hiternatum. 



flowers and the rhizomes, especially the roots. To decide the 

 question whether Enemion and L&ptojpyrum deserve generic 

 rank would require a thorough revision of all the species, 

 giving due attention to the structure of the rhizomes, which 

 is vet but imperfectly known, and very difficult to study from 

 herbarium material alone. Very remarkable are the Asiatic 

 species with two divaricate carpels, and we should not wonder 

 if a future investigator might refer these to a section of their 

 own, and distinct from Euisopyrum. The Californian /. stvp- 

 itatum, as indicated already by the specific name, ought not to 

 be placed side by side with the species of true Enemion. 



Isopyriim is altogether a very interesting little genus, not 

 onW from a morphological point of view, but also, if we con- 

 sider the geographical distribution, so excellently outlined by 

 Franchet (1. c). We see from his paper that the section 

 Enemion is the only one represented on this continent ; that 

 Euisopyrum is confined to Europe and Asia, and that Lep- 

 topyrum, which is monotypic, is only known from central and 

 oriental Asia; moreover that one member of the section Ene- 

 mion occurs in Asia, 1. Raddeanum Maxim (China and Japan). 

 The geographical center of the genus is no doubt to be sought 

 in Eastern Asia, where in accordance with Franchet all the 

 three sections are represented, and where Euisopyrum is 

 especially abundant. 



Brookland, D. C, Oct. 1907. 



EXPLANATION OF FIGURES. 



Figs. 1 and 2. — Roots of Isopyrwm hiternatum. Fig. 1. Transverse section 

 of a slender, secondary root ; C = cortex ; End.=endodermis ; Co = secondary 

 cortex ; L = leptome ; Camb. = cambium ; H = hadrome. Fig. 2. — Trans- 

 verse section of the slender portion of a monilif orm secondary root ; Ep. = 

 epidermis ; the other letters as above. Fig. 3. Transverse section of a 

 flowering stem ; St.=the stereomatic pericycle ; the other letters as above. 

 x320. 



