495 
Prunus virginiana L. Sp. Pl. i, 475 (1753). 
Wholly glabrous; leaves dull, ovate with acuminate base, thin, sharply serrate. 
In the Black Hills only a shrub or a low tree, at most 6 cm. in diameter. In damp, 
shaded canyons: Hot Springs, altitude 1,100 m., June 13; Sylvan Lake, altitude 
2,000 m., July 18 (No. 648). 
Prunus demissa (Nutt.) Walp. Rep. ii, 10 (1843); Cerasus demissa Nutt.; Torr, & 
Gr. Fl. i, 411 (1840). 
I inelude under this two forms. One is the common chokecherry of the western 
plains. It is generally glabrous; leaves oval with truncate or even cuneate base, 
thick, pale beneath. It differs from 2. virginiana in the much thicker leaves and 
sweeter fruit. Wherever I have seen it, it is a small tree—that is, it has one prin- 
cipal stem, with a rounded top. It has been named J’, demissa, although I doubt 
whether it is identical with the original. Rochford, altitude 1,600 m., July 12 (No. 
649). 
The other form has the young shoots, peduncles, and lower surface of the leaves 
pubescent, and even a little viscid, glabrate in age; leaves thick, shining above, 
paler beneath, elliptical or broadly oval. abruptly pointed or obtuse; base truncate 
or slightly cordate, or sometimes somewhat cuneate; flowers larger than in the pre- 
ceding two. A lowshrub, generally a few meters high. The largest stem I saw was 
about 5 cm. in diameter, with heartwood fully as dark as in I. serotina. It was 
growing in the same canyon as 7’. virginiana, from which it was casily distinguished. 
Hot Springs, altitude 1,100 m., June 15 and August 8 (No. 650). 
Spirza lucida Doug].; Hook. FI). Bor. Amer. i, 172 (1835), as synonym; 3S. betuli- 
folia Hook. loc. cit., not Pall. 
Professor Greene! has separated the American species from the Asiatic. 
Rapid City, altitude 1,000 m., June 25; Little Elk, altitude 1,100 m., June 28; 
Lead City, altitude 1,600 m., July 6 (No. 651), 
Luetkea cespitosa (Nutt.) Kuntze, Rev, Gen. Pl. i, 217 (1891); Spirwa cespiiosa 
Nutt.; Torr. & Gr. Fl. i, 418 (1840), 
Neither flowers nor fruit were found, The plant was growing on the hills around 
Little Elk, altitude 1,300 m., June 28 (No. 652). 
Opulaster opulifolius (L.) Kuntze, Rev. Gen. PI. ii, 949 (1891), var.; Spirwa opulifo- 
lia L. Sp. Pl. i, 489 (1753). 
My specimens from northern Nebraska and those I have seen from Colorado differ 
from the Opulaster opulifolius of the eastern United States in having pubescent ova- 
ries. ‘The pubescence remains, partly at least, until maturity, while in the eastern 
form the fruits are smooth and shining. ‘The ovaries are generally only three, and 
the leaves smaller and more rounded in outline. This form seems to connect this 
species and the following. Seeds obliquely pear-shaped, shining, carinate on one 
side. 
In the lower parts of the Hills near water. Rapid Creek, altitude 1,100 m., June 
25; French Creek, 10 miles below Custer, altitude 1,500 m., June 22; Hot Springs, 
altitude 1,050 m., August 2 (No. 653). 
Opulaster monogyna? (Torr.) Kuntze, Rev. Gen. Pl. ii, 949 (1891); Spirea 
monogyna Torr, Ann. Lyc. N. Y. ii, 1892 (1827). 
Very shrubby, 3 to 6 dm. high; leaves small, about 2.5 cm. long, round in out- 
line, deeply 3 to 5 cleft, teeth sharper than in the preceding; flowers half the size, 
ovaries mostly 2, very woolly. The leaves are perfectly smooth, in this point dis- 
agreeing with the description of Neillia torreyi, but otherwise agreeing with the 
'Pittonia, ii, 221. 
2Thus named by Professor Greene. I have seen specimens of an Opulaster, col- 
lected by Dr. Sandberg in Idaho, which fits the description of Spirwa monogyna Torr. , 
loe. cit., even as to the number of the carpels. This differs as much from my speci- 
mens as does Opulaster opulifolia. 
