60 UNIVERSITY OF COLORADO STUDIES 
become a handsome orange-red in autumn. The greenish-white clusters of berries 
remain during the winter. 
Altitude: 4,900 to 7,500 ft. Collections: Valmont Butte; Gregory Canyon; “foot- 
hills near Boulder” (Rydberg). 
Rhus trilobata Nutt. SKUNK BusH 
A low shrub of dry hillsides and rocky places; very common. The leaves become 
orange-red and copper-colored in autumn. 
Altitude 5,000 to 7,500 ft. Collections: Valmont Butte; hillside, Bluebell Canyon; 
South Boulder Canyon; ‘Boulder’ (Rydberg). 
ACERACEAE, Map te FAMILy 
Acer glabrum Torr. MouNntTAIN MAPLE 
A small tree or shrub along streams and gulches to the foot of the range. It would 
be valuable for ornamental purposes. 
Altitude: 4,900 to 9,000 ft. Collections: Bluebell Canyon; Sunshine Canyon; 
Sugarloaf Mountain; Eldora. 
Acer negundo Linn. Box ELDER 
A tree of lower foothills and plains regions along streams and on moist hillsides. 
Altitude: 4,900 to 6,500 ft. Collections: east of University campus; near Boulder; 
St. Vrain Creek below Lyons. 
Acer texanum Pax. Box ELDER 
This species is very similar to the preceding and probably has the same distribution. 
Collections: Bear Canyon; Bluebell Canyon; “foothills near Boulder” (Rydberg). 
FRANGULACEAE, BuckTHoRN FAMILY 
Ceanothus fendleri Gray. NEw JERSEY TEA 
A low, thorny shrub of dry hillsides; very common. 
Altitude: 5,500 to 9,500 ft. Collections: near Boulder; South Boulder Canyon; 
head of Gregory Canyon; hill north of Nederland; “Boulder; between Sunhsine and 
Ward” (Rydberg). 
Ceanothus pubescens (T. and G.) Rydb. NEw JEersEy TEA 
A small shrub on mesas and foothills. 
Collections: Bluebell Canyon; Eldora; “Boulder” (Rydberg). 
Ceanothus subsericeus Rydb. NEw JERSEY TEA. 
A low shrub on plains and lower foothills. 
Altitude: 5,000 to 6,500 ft. Collections: plains north of Marshall; Boulder Can- 
yon near mouth of Fourmile. 
Ceanothus velutinus Dougl. NEw JERSEY TEA 
Shrub with handsome dark green leaves growing in clumps; slightly moist soil of 
hillsides and gulches. 
Altitude: 6,000 to 9,000 ft. Collections: Bear Canyon; Eldora; near foot of Long’s 
Peak; ‘between Sunshine and Ward”’ (Rydberg). 
VITACEAE, GraprE FAMILY 
Parthenocissus vitacea Hitchc. VIRGINIA CREEPER 
Climbing in trees and over rocks in river-bottom forests and at canyon mouths. 
