495 



Prunus virginiana L. Sp. PI. i, 473 (1753). 



Wholly glabrous; leaves dull, ovate with acuminate base, thin, sharply serrate. 

 In the Black Hills only a shrub or a low tree, at ruost 6 cm. in diameter. In damp, 

 shaded canyons: Hot Springs, altitude 1,100 m., June 13; Sylvan Lake, altitude 

 2,000 m., July 18 (Xo. 648). 



Prunus demissa (Xutt.) Walp. Rep. ii, 10 (1843); Cerasus demiasa 'Sntt.; Torr. & 

 Gr. Fl. i, 411 (1840). 



I include under this two forms. One is the common chokecherry of the western 

 plains. It is generally glabrous; leases oval with truncate or even cuneatc base, 

 thick, pale beneath. It dift'ers from P. 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 P. demissa, although I doubt 

 whether it is identical with the original. Eochford, 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 Itroadly oval, abruptly pointed or obtuse; base truncate 

 or slightly cordate, or sometimes somewhat ctmeate; flowers larger than in the pre- 

 ceding two. A low shrub, generally a few meters high. The largest stem I saw was 

 about 5 cm. in diameter, with heartwood fully as dark as in /'. serofina. It was 

 growing in the same canyon as P. virginiana, from which it was easily distinguished. 

 Hot Springs, altitude 1,100 m., June 13 and August 8 (No. 650). 



Spiraea lucida Dougl.; Hook. Fl. Bor. Amer. i, 172 (1833), as synonym; S. hetuli- 

 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 caespitosa (Xutt.) Kuntze, Rev. Gen. PI. i, 217 (1891); Spira'a cwspiiosa 

 Nutt. ; Torr. *fe 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. 6.52). 



Opulaster opulifoUus (L.) Kuntze, Rev. Gen. PI. ii, 949 (1891), var. ; Spira-a opulifo- 

 /iaL. Sp. PI. i,489 (1753). 



My specimens from northern Nebraska and those I have seen from Colorado dift'er 

 from the Opulaster opuIifoUns 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 oblir^uely 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 mouogyna- (Torr.) Kuntze, Rev. Gen. PI. ii, 949 (1891); Spinva 

 mouogijna Torr. Ann. Lye. X. 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 Xeillia torreyi, but otherwise agreeing with the 



•Pittonia, ii, 221. 



-Thus named l)y Professor Greene. 1 have seen specimens of an Opulaster, col- 

 lected by Dr. Sandberg in Idaho, which fits the description of Spirwa monoggna Torr., 

 loc. cit., even as to the number of the carpels. This differs as much from my 8i)eci- 

 mens as does Opulaster opulifolia. 



