August 2, 1901.] 



SCIENCE. 



187 



etc. lu the wet valleys occur wild plums 

 (Primus americana), and the dwarf wild cherry 

 [Primus demissa), the former a shrub or small 

 tree, and the latter an upright little-branched 

 shrub, both usually forming close thickets. 



The trees are almost entirely confined to the 

 narrow belts which border the streams in the 

 canyons. Where the canyons are deep these 

 forest belts are entirely hidden as one glances 

 over the undulating surface of the plain. In 

 the eastern part of the Sand Hill region the 

 forest belts are wider, but in passing westward 

 they are narrower, the trees are lower, and 

 eventually they are mere straggling shrubs, 

 finally disappearing altogether. The species 

 are to a large extent those found in the eastern 

 portion of the State, there being but few cases 

 in which the Rocky Mountain trees have taken 

 possession of such protected areas. They are 

 the white elm, occasionally the red elm, the box 

 elder, red ash in small numbers, green ash in 

 larger numbers, sometimes the hackberry, with 

 the common cotton wood and several species of 

 willows, and occasional hawthorns, with here 

 and there the remnants of groves of bull pine 

 (Pinus scopulorum). 



THE GRASSY COVERING OF THE GREAT PLAINS. 



Those who visit the Great Plains for the first 

 time are usually interested in the grassy cover- 

 ing, which is the most marked feature of the 

 vegetation of the region. This covering is 

 mostly composed of a mixture of several species, 

 there being few places where a single species 

 occupies the ground to the complete exclusion 

 of all others. In the eastern portion of the re- 

 gion the grassy plants (including sedges) num- 

 ber about 130 species, in the central portion 

 (the Sand Hills) there are 170 species, while in 

 the western portion (the Foot Hills) there are 

 about 110 species. The eastern visitor will 

 notice with intei-est the ' buffalo grass ' (Bul- 

 bilis dacfyloides) in well-marked patches, the 

 different species of ' grama ' (Bouteloua oligos- 

 tachya, B. hirsuta, and B. curtipendula) scattered 

 over the surface, the 'wheat grasses' {Agro- 

 pyron pseudorepens and other species) usually 

 mingled with species of Bouteloua, the ' bunch 

 grasses ' {Andropogon scoparius, A. furcafus 

 and A. hallii) scattered in bunches over the 



surface, the ' needle grasses ' (Stipa sjxirfea, 

 S. comafa and S. viridida) scattered in bunches 

 over the surface, with other species known in 

 general as ' prairie grasses ' (species of Koeleria, 

 Eatonia, Sjwrobolus, etc.). Should he go into 

 the Sand Hills he would find the * blowout 

 grasses ' (Muhlenbergia pungens, EragrosHs Iri- 

 chodes, Oryzopsis cuspidata and Redfieldia flex- 

 uosa) in or on the margins of the naked sand 

 pits blown out of the hillsides. In the Foot 

 Hills he would find great areas covered almost 

 exclusively with the yellowish-brown foliage of 

 the little sedge {Car ex fil if olio) known through- 

 out the region under the names ' nigger wool,' 

 'nigger root,' or 'black root,' highly es- 

 teemed by the stockmen for its nutritious 

 qualities, and whose tough and durable black 

 roots form a persistent sod much used by the 

 settlers in the construction of their ' sod houses.' 



TREES OF THE RYDBERG COTTONWOOD. 



It may be of interest to some of the botanists 

 who will visit the Rocky Mountains this sum- 

 mer to know that they can see many fine 

 specimens of the ' Rydberg cottonwood ' {Popu- 

 lus acuminata) in the town of Colorado Springs. 

 They have been planted along the streets and 

 avenues mingled with trees of the common 

 cottonwood {Populus deltoidea). Especiallj'^ fine 

 trees may be seen along the east side of Cas- 

 cade avenue. Botanists will remember that in 

 1893 this tree was first described by Dr. Ryd- 

 berg in the Bulletin of the Torrey Botanical Club 

 (February, 1893) from material collected in the 

 canyons of the Wildcat Mountains of Western 

 Nebraska. Since the publication of the species 

 it has been found to extend from the Black Hills 

 southward to Southern Colorado, New Mexico 

 and Arizona. lu the plantings along the 

 streets of Colorado Springs this species was not 

 distinguished from the common cottonwood. 

 The two trees may, however, be very easily 

 distinguished by the shape and particular con- 

 tour of the leaves, which are rhomboid-lanceo- 

 late with serrulate margins in the new species, 

 in contrast to the broadly deltoid-ovate leaves 

 of the common species with their incurved- 

 deutate margins. 



Charles E. Bessey. 



The University of Nebraska. 



