36 ON THE GENUS ERIOGONUIM. 



six setaceous teeth; naked pedunculate flp^^ers are some- 

 times intermixed with the involucelli. Flowers small, 

 whitish, short cyathiform, seated upon articulated pedun- 

 cles; Iambics a little pubescent externally, oval, unequal. 

 Stamina &. Styles 3, longer than the stamina, pubescent 

 towards the base, apex obtuse. Receptaculum of the in- 

 volucelli producing smooth seise ilearly the length of the 

 peduncles. 



Habitat, On high and arid argillaceous hills from Fort 

 Mandan, or the great northern bend of the Missouri; to the 

 mountains? with the former. Flowers in August, 



OV the same alpine habit (viz. furnished with prostrate 

 or cespitose stems, and umbellated peduncleS'^Cr scapes) 

 are two other species of this genus collected on the north- 

 west coast of America by Mr. Archibald Menzies and now 

 deposited in the Herbarium of Sir J. Banks. They appear 

 to be described in Rees Encyclopedia under the names of 

 E' parvifoVmm and E, latifolium, and are said to be 

 shrubby; probably sufFruticose. 



Thus the genus Eriogonum^ as yet peculiar to North 

 America, approximating so nearly to Rheum, may pro- 

 bably form a numerous genus, whenever the great plains 

 of California^ the Columbia^ the Missouri and the Arkansa 

 shall be explored. 



To distinguish these two approximating genera with 

 more precision, we shall add the following description of 

 the seeds of Rheum Rhaponticum^ or officinal rhubarb. 



Calyx 6-parted, persistent, smooth, very small, unequal, 

 and closely investing the base of the seed, the three larger 

 oblong-oval segments appressed to the fruit, the three 

 smaller divisions reflected; stamens disposed by 3's oppo- 

 site the larger lacinise of the calyx. Seed acutely triangular. 



