REVISION OF RUMEX. 75 



species recognized by me as occurring within our flora, 

 eleven were characterized and named by Linnaeus in the first 

 edition of the Species Plantarum, and only five have been 

 named by American botanists. As a rule, though 

 puzzling to the novice, they are well marked, and I have 

 been able to complete my revision of the principal American 

 material without seeing the necessity of designating any 

 forms as new, though it may be that those mentioned 

 under salicifolius and crispus will ultimately demand recog- 

 nition as separate species. As illustrating the degree to 

 which one so disposed may multiply species, it may be 

 stated that in a very limited local flora (that of Lyon, 

 France), Gandoger in 1875 {fide Just, iii, 685,) described 

 sixteen new species, which other botanists are disposed to 

 consider only forms or hybrids of familiar species. The 

 practice of applying new specific names to known hybrids 

 is also calculated to increase unwarrantably the enumerated 

 species of a given region, since some of the docks and sor- 

 rels are known to hybridize quite freely. 



One of our twenty-one species is merely a ballast intro- 

 duction ; seven others are Old World weeds ; two (Acetosa 

 and salicifolius} are apparently arctic-alpines of wide dis- 

 tribution, while the other eleven belong essentially to the 

 North American flora. 



Among the more important references to the specific 

 delimitation of docks, aside from the monographs already 

 referred to, should be noted: Trimen, various papers in 

 Journal of Botany, about 1873; Haussknecht, Oesterr. 

 Bot. Zeitschrift, 1876, xxvi. (Just, 1876, part 2, 963 and 

 988),andMittheil. Geogr. Ges.f.Thiiringen,Jena, 1884, iii. 

 56-79 (Just, xii. part 2, 592), where many hybrids are 

 named ; Murbeck, Beitr. z. Kenntn. der Flora von Siidbos- 

 nien u. d. Hercegovina, in Lunds Universitets Aarsskrift, 

 1891, xxvii.; and Rechinger, Oesterr. Bot. Zeitschr., 1891, 

 400. 



The chief biological interest in the genus comes from 

 the protective acidity of the sorrels and some docks and the 



