ON THE GENUS ERIOGONUM. 27 



within the limits of the United States and its territories; 

 of the t;vo species briefly noticed by Mr. Pursh, disco- 

 vered by Mr. Bradbury and myself, scarcely any thing 

 is as yet distinctly known. In consequence of these and 

 other accessions, it appears necessary to modify the genus 

 with more precision. 



as it appears common to the whole order o{ Polygonete. 6th. Rimex, contain, 

 ing ar least forty-five species, all herbaceous. 7th. RJienniy containing eight 

 species, all herbaceous except R. htjbridum. The Rheum Rhaponticum, indige- 

 nous to Thrace; the R. undnlatum, to China and Siberia; the R. palmatum, to 

 China; the R. compactum, also to China and Tartar}; the R. tataricum, with ex- 

 tremely large leaves, to Lesser Tartary; the R. Ribes inhabits Persia, Lebanon, 

 and Carmel; the R. htjbridum belongs to Northern Asia, and is a shrub; lastly 

 the R. leucorhizum, discovered by Pallas, indigenous to the mountainous de- 

 serts of Songarica in Siberia. 8th. Kriogonnm^ containing about five or six 

 species, herbaceous or suffruticose, chiefly inhabiting the desert plains of North 

 America, on either side the Northern Andes. 9th. Triplaris, two species, both 

 trees; the T. Americana, native of the woods of Carthagena and Guianne, a tree 

 forty feet high, with a dense pyramidal summit, the second species grows also 

 in the forests of Carthagena. A revisal of the generic character of this genus 

 is also absolutely necessary, in order to separate it effectually from the genus 

 Eriogonumy there being at present as this order is now understood, not a single 

 artificial generic character given in the genus Triplaris, except its being a dio- 

 ecious plant, but what equally applies to Eriogomun, although there can be no 

 doubt of the existence of a distinct generic character, when we for a moment 

 consider the great disparity of habit. Jussieu, however, remarks that the seed 

 of this genus is a nut. 10th. CalUgomim, of which there are three species 

 with the C. JPallasia, which has been considered as a distinct genus, all shrubs 

 nearly destitute of leaves, with dichotomous and articulated brancheg; the C. 

 Rohigonoides, was tound by Tournefort on Mount Airarat; the C. comqswn is a 

 native of Egypt and Barbary; the C? Pa'dasia was discovered by him whose 

 name it bears, in the de.serts towards the Caspian sea. 11th. Koenigia i'slandica' 

 a small and rather succulent plant, peculiar to the isle of Iceland. To these 

 we may perhaps venture to add the Plegorhiza adstringcns of Molini, a plant of 

 Chili, which, as far as the description extends, appears to be almost a species 

 ©f Eriogomim, possessing in every respect its habitus. By Jussieu, for the 

 want of a correct description it was necessarily placed among the ** Planta; /«- 

 certce sedis,'* with an indication that it ought to he compared with this order, or 

 the Lauri. From this statement, It appears, that America possesses eight out 

 «f the twelve genera of the order Polygoneae. Most of the plants of this order 

 are more or less astringent and bitter. The most astringent of medixinc^s, the- 

 gura Kinoj is the produce of the Coccohba. 



