SALICACEAE. — POPULUS 39 



20. Populus tremula Linnaeus, Spec. 1043 (1753). 



Populus tremula, var. a typica Schneider, III. Ilandb. Lauhholzk. I. 19 

 (1904). — Ascherson & Graebner, Syn. Mitleleur. Fl. IV. 25 (1908). — Gom- 

 bocz in Math. Termesz. Kdzl. XXX. 126 (Monog. Gen. Populi) (1908). 



WESTERN SIBERIA. 



Populus tremula, var. Davidiana Schneider. See p. 24. 



Populus tremula, var. Davidiana, f. tomentella Schneider. See p. 25. 



21. Populus rotundifolia Griffith, Notul. PI. As. IV. 382 (1854); Icon. PI. As. 

 IV. t. 546 (1854). — Dode in Mem. Soc. Nat. Autun, XVIII. {Extr. Monog. 

 Ined. Populus, sub Errata et Addenda, Esp^ce 34) U905). — Gombocz 

 in Math. Termesz. Kdzl. XXX. 130 {Monog. Gen. Populi) (1908). 



Populi spec. Griffith, I tin. Notes, II. No. 881 (1848). 



Populus microcarpa Hooker f., Fl. Brit. Ind. V. 639 (1888). — Dode in Mem. 



Soc. Nat. Hist. Autun, XVII. (Extr. Monog. Ined. Populus, 32, t. 11, fig. 34) 



(1905). 



INDIA. Bhutan : W. Griffith (No. 4495). This specimen may be the type of 

 Hooker's P. microcarpa: Bhutan, about Panga and towards Chupeh, alt. 2500 m., 

 Griffith. 



Having seen only one fruiting specimen of the typical P. rotundifolia by the 

 kindness of the Keeper of the Kew Herbarium, I cannot decide whether var. 

 Duclouxiana Gombocz to which I have referred some of Wilson's plants from 

 Szechuan is sufficiently distinct. The shape of the leaves is variable, but the 

 fruits of the type are very small, and the pedicels are glabrous. 



Populus rotundifolia, var. Duclouxiana Gombocz. See p. 25. 



SPECIES INCERTAE. 



Populus Bonati Leveill6 in Monde Plant. XII. 9 (1910); in Fedde, Rep. Spsc. 

 Nov. VIII. 445 (1910). — Gombocz in Bot. Kdzl. X. 25, fig. (7) (1911). 



CHINA. Yunnan. 



Populus Bonati has been collected in Yunnan : Pa-ta-ouan, pres Pin Tchouan, 

 March 3, 1907, Jean Py (No. 665 (type ex LeveilM), and according to Gombocz 

 also by Ducloux at Tchong-chan. Gombocz considers P. Bonati a distinct species 

 on account of its trilobed or trifid stigmas. His figures, 1. c. p. 26, represent rather 

 old female flowers of P. tremula, P. Bonati and P. adenopoda, and I have never seen 

 such narrow and round stigmas on young flowers. The shape of the lobes of the 

 stigmas seems variable even in the same species. The male flowers of P. Bonati are 

 described with 12-15 stamens. In the flowers of tj^pical P. adenopoda I have never 

 found more than 7-9 stamens. I suggest that P. Bonati may be rather a form 

 of P. rotundifolia, var. Duclouxiana than a form of P. adenopoda. 



Populus alaschanica Komarov in Fedde, Rep. Spec. Nov. XIII. 233 (1914). 



SOUTHERN MONGOLIA. Prov. Alashan : "ad ripas canalium irriga- 

 torium et lacuum circa oppidum Dyn-juanj-in," March 27, April 15, June 4, 1908, 

 Tshetyrkin (male and female types, ex Komarov). 



According to the author this species belongs to Sect. Leuce, but I do not quite 

 understand Komarov's remark which follows: "An origine hybrida inter P. tre- 

 mula L. et P. Przewalskii Max. (sect. Tacamahaca?) Populus tremula in vicinitate 

 deest autem perfecte." The description is very short and rather insufficient. 



