210 BOTANICAL GAZETTE [march 



pubescent or glabrous; and the only constant character I can find m the Van- 

 couver Island trees is the presence of the dense covering of hairs on the rachis 

 of the male and female inflorescence and on the disk of the pistillate flower. 



Populus arizonica, n. nom. — Populus mexicana Sargent, Silva 

 N. Am. 14:73. pi. 733 (not Wesmael). 1902; Man. 162. fig. 136. 

 1905. — A photograph of the type specimen of P. mexicana Wesmael 

 collected by Berlandier between Tampico and Rial del Monte in 

 May 1827, kindly sent to the Arboretum by the late Casimir 

 DeCandolle, shows clearly that the tree with small fruit which 

 is common in the neighborhood of Tucson, Arizona, was wrongly 

 referred to Wesmael' s species. For the Arizona tree I now suggest 

 the name of P. arizonica. It is well distinguished from the other 

 cottonwoods of the United States by the small fruit, which does 

 not exceed 5 mm. in length. 



Arizona. — Common up to 2200 m. above sea level. Santa Catalina 

 Mountains, Pima County, C. G. Pringle, 1881, A. Rehder, August S, 1914 

 (no. 256) ; Bear Creek, foot of Santa Catalina Mountains, ^. iJeMer, August 30, 

 1916 (no. 452); Sabino Canyon, Santa Catalina Mountains, /. W. Tourney, 

 February 20, 1894, A. Rehder, August 7, 1914 (no. 233), September i, 1916 

 (no. 500) ; near Tucson, Pima County, Engelmann and Sargent, September 30, 

 1880, /. W. Tourney, February 27, 1894, February 1898, C. S. Sargent, 

 February 27, 1894, March 27, 1916; Douglas, Cochise County, A. Rehder, 

 August 27, 1916 (no. 447a, a planted street tree); Yavapai County, near 

 Clarkdale, A. Rehder, September 11, 1916 (no. 555), near Camp Verde, 

 September 9, 1916 (no. 542), Beaver Creek, near Camp Verde, September 8, 

 1916 (no. 540), banks of Gannett Creek, Prescott, September 4, 1916; on 

 Salt River, near the Roosevelt Dam, Gila County, W. H. Goddard, June 191 7; 

 Coconino County, Sycamore Canyon, Percival Lowell, September 191 5, A. 

 Rehder, September 14, 1916 (no. 573); Hermit Creek, Grand Canyon of the 

 Colorado, Alice Eastwood, April 10, 1917 (no. 6002); Turkey Creek, near 

 Flagstaff, C. 0. Lampland, March 191 7; Canyon Diablo, C. 0. Lampland, 

 April 5, 191S (these specimens have only very young flower buds and may 

 belong to another species). 



California.— A sterile branch collected by A. Rehder July 23. 1914 

 (no. 128), on Mill Creek above Forest Home, San Bernardino Mountains, is 

 doubtfully referred to this species. 



New Mexico.— Near Silver City, Grant County, E. L. Greene, 1880 (dis- 

 tributed as P. Fremontii), 0. F. Arthur, March 16, 1918, M. W. Talbot, April i, 

 1918, /. A. Scott, May 18, 1918. 



In the neighborhood of Tucson, where this poplar has been planted in 

 considerable numbers, it is a magnificent tree 20-28 m. in height with a trunk 



