HEXANDRIA— DIGYNIA. Oxyria. 189 



Rheum digynum. Wahlenb. Lapp. 101. t. 9.f. 2. 



Lapathum n. 1595. Hall. Hist. v. 2. 273. 



Acetosa rotundifolia repens Eboracensis, folio in medio deliquium 

 patiente. Moris, v. 2. 583. sect. 5. t.3G. f. last but one. Rail 

 Syn. \43. 



A. repens Weslmorlandica, cochleariae foliis, apicibus nonnihil si- 

 nuatis. Pluk. Almag.S. Phyt. t. 252. f. 2. 



A. rotundifolia alpina. Bauh.Pin.WA. Prodr.ob. 



A. rubra. Martens Spitzberg. 41 . Italian ed. 98. 



Welch Sorrel. Pet. H. Brit. t. 3./. 4. 



In mountain bogs, rills, and moist clefts of rocks. 



In Wales, Scotland, and the north of England, about the summits 

 of the loftiest mountains, plentiful. 



Perennial. June. 



Root strong, running deep into the ground, subdivided and tufted 

 at the crown. Steyns solitary, erect, a span high, roundish, 

 striated, panicled, almost leafless. Leases almost all radical, on 

 \ong\sh footstalks, kidney-shaped, bright green, somewhat wavy, 

 abrupt, with more or less of a central sinus ; ribs all radiating 

 from the insertion of the footstalk. Panicle erect, branched, twice 

 as tall as the leaves. Bracteas sheathing, membranous. Fl. 

 small, drooping, on capillary, whorled, simple stalks. Anth. and 

 stigm. reddish, as well as the wing of the seed. 



The whole herb is powerfully and gratefully acid, vpith some as- 

 tringency. Sir John Hill, it seems, first separated this plant 

 from Rumex, and gave it the above generic name. Sometimes, 

 as Linnaeus says, a blind hen meets with a grain of corn. Gaert- 

 ner approved of the suggestion, though he did not follovv it ; but 

 Mr. Brown has fully established the name and the genus. The 

 intelligent Dr. Wahlenberg conceived our Oxyria to be a Rheum, 

 deprived of one third of the due number of parts in the fructifi- 

 cation, of which there are many similar examples. But though 

 these two genera agree together in having a central, not lateral 

 or marginal, embryo, in which they differ from Rumex ; such a 

 character, too obscure for common practical use, can only be 

 taken as indicative of generic distinctions or agreements, here 

 confirmed, and essentially marked, by the respective numbers of 

 parts of the flower. By these Rheum differs from Rumex on the 

 one hand, as Oxyria does on the other. Rumex is deprived of 

 a third part of the stamens of Rheum, Oxyria of one third of the 

 styles of each. Its winged seed, and central embryo, accord with 

 Rheum; its distinct calyx and corolla with Rumex ; for the Na- 

 tural Order to which they all belong, is one in which the nature 

 of these last parts is not uniform throughout. The radiating ribs 

 of the leaves in Oxyria, pointed out by Dr. Wahlenberg, as evin- 

 cing some affinity to Rheum, occur in several Rumices ; witness 

 R. scutatus, otherwise closely related to Oxijria. 



