[ 401 ] 



XXI. On the Eriogonc£e, a Tribe of the Order Polygonacese. By George 



Bentham, Esq., F.L.S. 



Read April 7th, 1835. 



1 HE genus Eriogoman was first established by Michaux in his Flora Boreali- 

 Americana, upon a Carolina plant distinguished from other Polygonaceie, not 

 so much by the organs of fructification, which are not very essentially different 

 from those of Rheum, as by the involucrate inflorescence and the absence of 

 the ochrece, or sheathing stipules, observable in some shape or other in every 

 other genus of the order. To the single species described by Michaux (E. to- 

 mentosum), Nuttall and Pursh added two others gathered by the former botanist 

 in the plains of the Missouri [E. flaviim and E. pauclforum), and Smith in 

 Rees's Cyclopaedia described two more brought by Menzies from the coast of 

 California {E. latifollum and E. parvifol'mm) . These five North American 

 species have now been increased to thirty-three by the discoveries of Mr. 

 Douglass in New California and the North-west district, and of Mr. Nuttall, 

 Dr. Torrey, Mr. Drummond, and others, in the Rocky Mountains, Arkansa 

 territories, and province of Texas; and all are equally distinguished by their 

 involucrate inflorescence and absence of stipulae, at least to the lower or true 

 cauline leaves. But a considerable difference in habit has induced me not 

 only, at the suggestion of Mr. Brown, to separate generically five species with 

 uniflorous involucres, but, amongst these, to isolate one (Miicronea), which 

 lias a compressed and bidentate involucre formed of two leaves, instead of a 

 triangular sexdentate one formed of six leaves, as in the other four species 

 {Chorlzmifhe, Br.). The latter genus is further confirmed and augmented by 

 seven species collected in Chili by Macrae, Cuming, Bridges, &c., giving a 

 total of forty species comprised in the three genera. 



The whole of these plants have al! the essential characters of Polygonacece, 

 thus stated by Brown {Prodr. p. 418) : 



