1922] REHDER, TWO NEW ASIATIC POPLARS 225 



TWO NEW ASIATIC POPLARS 



Alfred Rehder 



Populus Purdomii, spec. nov. 



Arbor; ramuli juveniles teretes vel subteretes, glabri, annotini ochracei 

 vel pallide flavo-brunnei; gemmae acutae, glabrae, viscosae. Folia ovata, 

 vel anguste ovata, 10-13 cm. longa et 6-8.5 cm. lata, interdum ad 16 cm. 

 longa et ad 13 cm. lata, ea turionum saepe oblongo-ovata ad 25 cm. 

 longa et ad 15 cm. lata, acuminata, basi rotundata et plus minuse sub- 

 cordata, margine denticulato-serrata vel crcnato-serrata dentibus brevibus 

 mucronulatis, supra glabra margine interdum ciliolato excepto, opace 

 viridia nervis flavescentibus, subtus albescentia, sparse pilosula vel 

 densius ad nervos et venulas, interdum glabra; nervis et nervulis distinctis 

 elevatis; petioli 2.5-5 cm. long longi, ei turionum plerique paullo breviores. 

 Amenta tantum fructifera visa, ad 11 cm. longa glabra; capsulae sessiles 

 vel subsessiles, glabrae, globoso-ovoideae circiter 7 mm. longae, 2-3-valvae, 

 basi perianthio parvo irregulariter lobato cinctae. 



China. Shensi: Tai-pai-shan, W. Purdom, No. 1111 (type), 1910, No. 1110 

 (sterile), 1910. Southwestern Kansu: near Kagoba, alt. 2300-2600 m., 

 F. N. Meyer, Nos. 1816, 1993, (sterile) October 30, 1914; Yin kuan dien, F. N. 

 Meyer, No. 1945 (sterile), September 23, 1914. Also the following specimens 

 seem to belong here: Szechuan: Lungan Fu, Tu-ti-liang-shan, alt. 2300- 

 3000 m., E. H. Wilson, No. 4578, August 1910, west of Kuan Hsien, Pan-lan-shan, 

 alt. 2600-3300 m., E. H. Wilson, No. 4346, October 1910. 



Cultivated. Chico, Calif., Field Exper. Station of U. S. Department of Agri- 

 culture, under S. P. I. No. 39900 (from Kagoba,) C. R. Howard, April 2, 1916. 

 Arnold Arboretum (plant received from Chico under S. P. I. No. 39900), A. 

 Rehder, August 22, 1922. 



This new species seems to be most nearly related to P. suavcolens 

 Fischer and to P. szechuanica Schneider, but it differs from both in its 

 prevailingly 2-valved capsules. In the shape and size of its leaves it 

 resembles the latter, but the leaves are generally smaller and somewhat 

 narrower, and the branchlets and even the more vigorous shoots are terete 

 and not angled. From P. suaveolens it may be further distinguished by 

 the larger, more coarsely glandular-serrate leaves always rounded and 

 more or less subcordate at base and by the usually duller volored branch- 

 lets. The specimens from Shensi and Kansu have the under side of the 

 leaves more or less pubescent but Purdom 's No. 1110 is quite glabrous 

 like the specimens from Szechuan; the pubescence, however, seems vari- 

 able, as in Meyer's No. 1816, one leaf has the midrib, veins and veinlets 

 distinctly pilose, while two other leaves attached to the same branch are 



glabrous and one is slightly pilose. 



Photographs taken by F. N. Meyer near Kagoba in 1914, under Nos. 



12170 and 13165, are in the collection of photographs of this Arboretum. 



Populus Purdomii was introduced by F. N. Meyer, from Kagoba and 



subsequently distributed by the U. S. Department of Agriculture under 



