208 Rhodora [DECEMBER 
in the “ P. deltoides” of the Delaware country. The latter is com- 
monly planted in or about 
Washington where I have 
observed it, and its leaves 
when unfolding are invari- 
ably glabrous and shining. 
Through the courtesy of Prof. 
B. L. Robinson I have been 
able to study material of the 
true P. nigra of Europe. 
Typical leaves of the latter 
l are generally rhombic-acumi- 
Fig. 8. nate. There is, however, a 
Fig. 8. Populus deltoides. X ij. wide range of variation of the 
Fig. 9. Populus deltoides. X 4. z 
leaves of the two species and 
some forms of both are nearly identical in outline. The pubescence, 
however, even in full grown leaves, serves to distinguish the Old World 
species from our own. 
[ 
D 
SYNOPSIS OF THE SPECIES (SECT. AIGEIROS). 
Leaves of a cordate type. 
POPULUS VIRGINIANA Fouger (ff. 6-7). Normal leaves (excl. petiole) 
8-10 em. long and nearly as broad, ciliolate; the base varying from 
nearly truncate to cordate (f. 6.): rootshoot leaves larger (f. 7.): sta- 
mens 30-50; anthers yellow (reddish at first). Fl. Apr-May. Along 
Potomac River. 
Leaves of a deltoid or ovate type. 
Leaves predominantly deltoid. 
PopuLus DELTOIDES Marsh. (ff. 8-10). 
Normal leaves (excl. petiole) 8-10 em. long 
and nearly as broad (ff. 8 and 10): root 
shoot leaves larger, 12-15 cm. long and 
nearly as broad (f. 9): stamens 30-50; 
anthers dark red. Fl. March-April. Along 
Delaware River. In cultivation. 
Leaves predominantly ovate. 
PoPULUS ANGULATA Ait. Hort. Kew. 3: 407. 
1789. Michx. f. Hist. Arb. 3: 302. t. 12, Fig. 10. Populus 
1813. Schneider, Ill. Handb. 1:9.f.1,0-p,  deltoides. x4. 
1904 (ff. 11-13.) Normal leaves (excl. petiole) 8-10 cm. long, 
nearly as broad; the base varying from rounded to nearly trun- 
cate (f. 12): rootshoot leaves 12-18 cm. long, 12-15 cm. broad; the 
base rounded: flowers unknown. The young branches are of an 
olive brown color, 5-winged (See Michx. f., l. c. t. 12.), with seat- 
