BETULACEAE. — BETULA 483 



Beluln humilis, var. Ruprechtii Kegel in Nouv. Mem. Soc. Nat. Mnsc. XIII. 

 pt. 2, 109, t. 8, fig. 40-47 (Monog. Betulac. 51) (1861); in DeCandolIe, Prodr. 

 XVI. pt. 2, 174 (1868). — Herder in Act. Horl. Petrop. XII. 66 (1892). 



CHINA. Chili: Central and west Weichang, 1910, W. Purdom (No. 104). 



NORTHEASTERN ASIA. Transbaikalia : swamp near Sryetinsk, August 

 13, 1903, C. S. Sargent (fruits); " Dahuria " (ex Herb. Hort. Petrop.). Amur 

 and Ussur i : Amur, 1859, C. Maximowicz; " am untern Amur: haufig auf nas.sen 

 Wiesen in der Niederung bei Ivitsi," July 29, 1856, C. Maximowicz (tj^pe of var. 

 Ruprechtiana, ex Trautvetter) ; " am linken Schilka-Ufer gleich unterhalb der 

 Scheltuga-Miindung," May 19, R. Maack (type of B. palustris Gmclini, ex Maack & 

 Ruprecht) ; " am mittleren Amur oberhalb der Garin-Mundung," July 25, R. Maack 

 (type of B. ovaliJoUa, ex Maack & Ru])recht) ; same place, R. Maack (type of B. 

 relicidata, ex Maack & Ruprecht) ; " Amur med.," May 27 and July 5, 1891, S. Kor- 

 shinsky; "am oberen Amur gleich unterhalb der Onon-Miindung am Hnken 

 Amur-Ufer," June 7, R. Maack (type of B. palustris, var., ex Maack & Ruprecnt); 

 " Amur superior," September 1, 1891, 5. Korshinsky {huits). Korea: "fluvium 

 Tumingan, di.strictus Musang, vallis Pakapen," June 8, 1897, V. Komarov (No. 

 488; young fruits); "in silvis pede montis Pai-ktu-san" (ex Nakai). 



1 do not know where Pallas' type came from, and I am not sure whether all these 

 forms mentioned in the sjmonymy above belong to the typical B. fruticosa Pallas. 

 It is probable that there are different forms and probably hybrids, too, mixed with 

 that species. Without having seen the type specimens of Pallas, Ruprecht, Traut- 

 vetter and Regel it is useless to try to distinguish any varieties. 



Sect. 4. EXCELSAEi W. D. Koch, Syn. Fl. Germ. Helv. ed. 2, 760 (1843). 



Betula, sect. Albae Regel in Bvll. Soc. Nat. Mosc. XXXVIII. pt. 2, 396, incl. 

 Sect. Dahiiricae (1865). — Prantl in Engler & Prantl, Nat. Pflanzcnfam. 

 III. abt. 1, 45 (1887). — Koehne, Deutsche Dendr. 107 (1893). — Schneider, 



III. Handb. Laubholzk. I. 109 (1904). 



Betula, sect. Eubetula, subsect. Albae Regel in De Candolle, Prodr. XVI. 2, 

 162 (1868), incl. subsect. Do/i-wncae. — Winkler in Engler, Pflanzenr. IV.-61, 

 74(1904), incl. B. fruticosa. — Ascherson & Graebner, Syn. Mitteleur. Fl. 



IV. 390 (1910). 



Subsect. a. Dahitricae Schneider, n. comb. 

 Betula, sect. Dahuricae Regel, in Bull. Soc. Nat. Mosc. XXXVIII. 396 (1865), 



excl. B. urticifolia. 

 Betula, sect. Albae, subsect. Dahuricae Regel in De Candolle, Prodr. XVI. pt. 2, 



174 (1868), excl. B. urticifolia. — Schneider, III. Handb. Laubholzk. I. 109 



(1904). 

 Betula, subgen. Dahuriae [sic] Nakai in Tokyo Bot. Mag. XXIX. 40 (1915). 



Possibly there are American forms which might be referred to this subsection. 

 The whole classification of the difficult species and forms of a genus like Betula must 

 be a provisional one as long as we cannot refer to all the forms of the whole genus. 



25. Betula davurica Pallas, Reise, III. 422, not., 321, 421, t. Kk, fig. 4 a-b 

 (1776), fide Ledebour; Fl. Ross. I. pt. 1, 60, t. 39, tantum fig. A (1784). — Lede- 

 bour, Fl. Ross. HI. pt. 2, 651 (1850). — Turczaninow in Bull. Soc. Nat. Mosc. 

 XXVII. pt. 1, 401 (1854); Fl. Baical.-Dahur. II. 128 (1856). —Trautvetter in 

 Bull. Soc. Nat. Mosc. XXX. 445, t. 7 (1857). — Maximowicz in Mem. Sav. Etr. 



1 Koch's name refers to the arborescent species B. alba Linnaeus and B. pubes- 

 cens Ehrhart in contrast to the "Humiles" and does not refer to B. excelsa Aiton. 



