378 BOTANICAL GAZETTE [NOVEMBER 
the narrow-leaved cottonwood, is the largest and most frequent species. The 
willows include Salix irrorata and S. exiguus, forming shrubby clumps; and S. 
Bebbiana, S. amygdaloides, and S. lasiandra, small trees. The hackberry, 
Celtis reticulata, is perhaps more typically found scattered along stream-sides in 
quite exposed places than with other trees. It is also common in such habitats 
in New Mexico. Certain plants common in the canyon forest are also quite 
characteristic, in the rather less exposed stream-side situations, replacing the 
cottonwoods and willows in small areas, or intermingling with them. Such 
plants are Alnus tenuifolia, Betula fontinalis, Acer Negundo, and the shrubby 
Cornus stolonifera. Scattered plants of the mixed shrub association are also 
frequently seen: Bossekia, Ribes, Rosa, Crataegus, Prunus demissa, and others. 
CANYON FOREST ASSOCIATION 
RAMALEY (12, p. 127); Younc (28, PP. 333, 335), Alnus-Betula-Corylus 
assemblage; (/.c., p. 334), Crataegus assemblage, etc.; DANIELS (4, pp. 21, 27)- 
The canyon forest, which contains many of the deciduous tree 
species of the foothills, is typically developed in local mesophytic 
stations, such as the slopes and bottoms of narrow canyons, in 
which the soil is moist (usually from seepage), and the air compara- 
tively humid, due to the shade and the shelter from wind. A 
selected list of species is here given: 
PLANTS OF FOOTHILLS CANYON FOREST ASSOCIATION 
Trees 
Alnus tenuifolia Prunus american 
Betula fontinalis Prunus demissa (N utt.) Dietr.s (ch) 
Salix Bebbiana (2) Robinia neomexicana ( 
Populus tremuloides (i) Acer glabrum (ch) 
Amelanchier alnifolia (/z) Acer Negundo (/) 
runus pennsylvanica (ch) Crataegus coloradensis et spp. 
Shrubs 
Corylus rostrata (/) Rhus Rydbergii (2) 
Ribes longiflorum Vitis vulpina (/) 
Physocarpus Ramaleyi (i) Parthenocissus vitacea (/) 
Rosa Sayi et spp. Viburnum pauciflorum (/) 
$ Jones (8, p. 35) fails “‘to see any ground for Netson’s P. melanocarpa, 2 
though Nutra. describes his as red-fruited, for we know that this species has 
red till dead ripe, when it turns black,” 
