POPULUS MACDOUGALII : A NEW TREE FROM THE 

 SOUTHWEST 



By J. N. ROSE 



(With One Plate) 



In 1904 Dr. D. T. MacDougal obtained photographs and specimens 

 of a strange poplar, which I then considered new, but the description 

 of which I reserved for further information. Recently I received 

 the following communication from Mr. S. B. Parish : 



" I am sending you under another cover specimens of a Populus 

 which does not well agree with any species of which I have a descrip- 

 tion. It belongs in the delta lands of the Colorado River, at least to 

 Yuma, where it is abundant in the bottom lands on both sides of the 

 river. It also comes into the Salton Sink, along the Alamo and New 

 rivers. In the settled part of the Sink it is very generally cultivated, 

 but is not indigenous. The Indio and Mecca specimens are from 

 cultivated trees. 



" I have seen no very large trees, and I am inclined to believe that 

 it does not attain to a large size, or to a very great age. But this 

 opinion might be modified by further observation." 



POPULUS MACDOUGALII Rose, sp. nov. 



Small tree, usually 10 meters high, or more, the trunk proper about 

 5 meters long ; branches strict, ascending ; bark on trunk, when 

 mature, light gray, moderately fissured ; bark on branches, even the 

 larger ones, smooth and light gray, appearing almost white ; twigs 

 light gray ; young growth very pubescent, but the two-year-old parts 

 glabrate ; mature leaves much wider than long, often 1 1 cm. broad, 

 moderately acuminate, truncate at base, sometimes slightly cuneate, 

 the margins with shallow crenations, when young, with very pubes- 

 cent petioles and less pubescent blades ; mature petioles strongly flat- 

 tened, often scantily pubescent ; racemes 5 to 6 cm. long ; pedicels 

 short (3 to 5 cm. long). 



Type in the United States National Herbarium, No. 692069, col- 

 lected on Mecca Flats, in the Salton Basin, California, February 28, 

 1913, by S. B. Parish (No. 8471). 



Smithsonian Miscellaneous Collections, Vol. 61, No. 12 



