482 WILSON EXPEDITION TO CHINA 



Regel, 1. c, distinguish several varieties, and I believe there are also hybrids, 

 probably of different origin. Such forms, however, can only be correctly inter- 

 preted by comparing all the known material. 



23. Betula humUis Schrank, Baier. Fl. I. 420 (1789), excl. cit. Gmelinii.i — 

 Spach in Ann. Sci. Nat. ser. 2, XV. 193 (1841). — Ledebour, Fl. Ross. 111. pt. 2, 

 653 (1S50). — Dippel, Handb. Laubholzk. II. 180 (1892). — Koehne, Deutsche 

 Dendr. 112 (1893). — Hempel & Wilhelm, Bdume & Strducher, II. 28, fig. 122 A-D 

 (1894). — Schneider, III. Handb. Laubholzk. I. 103, fig. 55 b-e, 56 f-i, 57 c 

 (1904). — Ascherson & Graebner, Syn. Mitteleur. Fl. IV. 404 (1911). 



Betula fruticosa Ledebour, Fl. Alt. IV. 246 (1833), excl. syn. Pallasii et 



Gmelinii. 

 Betula humilis, var. genuina Regel in Nouv. Mem. Sac. Nat. Mosc. XIII. pt. 2, 



106, t. 9, fig. 44-55 {Monog. Betulac. 48) (1861), excl. syn. Pallasii; in De 



Candolle, Prodr. XVI. pt. 2, 174 (1868). — Herder, in Act. Hort. Petrop. 



XII. 65 (1912). — Winkler in Engler, Pflanzenr. IV.-61, 74 (1904). 

 Betula humilis, var. commutata Regel, in Nouv. Mem. Sac. Nat. Mosc. XIII. 



108, t. 10, fig. 4-14 {Monog. Betulac. 50) (1861). 



For further sjoionyms and citations see Ascherson & Graebner, 1. c. 



The typical B. humilis Schrank does not occur, I beheve, in eastern Asia, and 

 seems to reach the eastern limit of its range in the western Altai. The forms 

 of eastern Siberia, referred to B. humilis by duTerent authors, may belong to B. 

 fruticosa Pallas and to B. glandulosa, var. sibirica Schneider. Probably also to other 

 forms not yet sufficiently understood, as B. Middendorffii Trautvetter & Meyer. 



24. Betula fruticosa Pallas, Reise, III. App. 758, t. Kk, fig. 1-3 (1776) ; Fl. Ross. 

 I. pt. 1, 62, t. 40 A-C (in tab. sub B.fruticans) (1784). — Ledebour, Fl. Alt. IV. 

 246 (pro parte) (1833); Fl. Ross. III. pt. 2, 653 (1850). — K. Koch, Dendr. II. 

 pt. 1, 658 (1872), exclud. syn. Ledebourii. — Dippel, Handb. Laubholzk. II. 169 

 (1892). —Herder in Act. Hort. Petrop. XII. 59 (1892). — Koehne, Deutsche Dendr. 

 Ill (1893). — Komarov in Act. Hort. Petrop. XXII. 50 {Fl. Mansh. II.) 

 (1903). — Schneider, III. Handb. Laubholzk. 1. 103, fig. 56 d-e, 57 b-bi (1904). — 

 Winkler in Engler, Pflanzenr. IV.-61, 87 (1904). — Nakai in Jour. Coll. Sci. Tokyo, 

 XXXI. 203 {Fl. Kor. II.) (1911); in Tokyo Bot. Mag. XXIX. 43 (1915). 



Betula, y humilior palustris GmeUn,^ Fl. Sibir.l. 167, t. 36, fig. 2 (1747). 



Betula Gmelini Bunge in Man. Acad. Sav. Etr. St. Petersbourg, II. 607 in 

 observ. {Verz. Altai-Geb. Pfl. 85) (1835); Verz. AUai-Gsb. Pfl. ed. 8°, 113 

 (1836). — Trautvetter, PI. Imag. Fl. Ross. 10, t. 5 (1844). — Ledebour, Fl. 

 Eoss. III. pt. 2, 6.52 (1850). 



Betula palustris Gmelini Ruprecht in Bidl. Acad. Sci. St. Petersbourg, XV. 376 

 (1857); in Mel. Biol. II. 6, 558 (1858). 



Betula palustris, var. Ruprecht, 1. c. 377 (1857); 1. c. 559 (1858). 



Betula ovalifolia Ruprecht, 1. c. 378 (1857); 1. c. 560 (1858). 



Betula reticulata Ruprecht, 1. c. 378 (1857); 1. c. 561 (1858). 



Betida fruticosa, var. Ruprechtiana Trautvetter in Mem. Sav. 6tr. Acad. Sci. 

 St. Petersbourg, IX. 254 (Maximowicz, Prim. Fl. Amur.) (1859). —Wink- 

 ler in Engler, Pflanzenr. IV.-61, 87 (1904). 



1 See under B. fruticosa Pallas. 



2 This Birch is cited by Schrank {Baier. Fl. I. 420 [1789]) under his B. humilis. 

 According to the figure it may be a form of B. fruticosa Pallas, who cites Gmelin, 

 and it was named B. Gmelini by Bunge and Betula palustris Gmelini by Ruprecht. 



