SCIENTIFIC EXPEDITION TO NORTHWESTERN COLORADO 



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Collection of Plants from Ridges 



Pinus edulis Engelm. 

 Sabina utahensis (Engelm.) Rydb. 

 Ephedra antisylphitica E. A. Mey. 

 Eriocoma cuspidata Nutt. 

 Hordeum jubatum L. 

 Sitanion pubiflorum J. G. Smith 

 Quercus gunnisonii (Torr.) Rydb. 

 Quercus utahensis (DC.) Rydb. 

 Eriogonum alatum Torr. 

 Eriogonum tristichum Small 

 Atriplex canescens (Pursh) James 

 Atriplex confertifolia (Torr.) Wats. 

 Odostemon aqui folium (Pursh) Rydb. 

 Ribes vallicola Greene 

 Fendlera rupicola Engelm. & Gray 

 Cercocarpus parvifolius Nutt. 

 Kunzia tridentata (Pursh) Spreng. 

 Amelanchier oreophila A. Nels. 



A melanchier rubescens Greene ? 

 Peraphyllum ramosissimum Nutt. 

 Lupinus greenei A. Nels. 

 Touterea speciosa Osterh. 

 Asclepiodora decumbens (Nutt.) A. Gray 

 Gilia aggregata (Pursh) Spreng. 

 Castilleja flava Wats. 

 Symphoricarpos occidentalis Hook. 

 Artemisia tridentata Nutt. 

 Artemisia wrightii Gray 

 Aster nelsonii Greene 

 Brickellia microphylla Gray 

 Carduus undulatus Nutt. 

 Chrysopsis arida A. Nels. 

 Chrysothamnus graveolens (Nutt.) Greene 

 Coleosanthus albicaulis Rydb. 

 Petradoria pumila (T. & G.) Greene 

 Solidago trinervata Greene 



Oak chaparral. — In northwestern Colorado this formation is a 

 thicket of Quercus utahensis and Q. gunnisonii. These two species 

 seldom grow higher than ten or twelve feet. At lower altitudes oak 

 chaparral forms the transition formation between sage-plain and ridge. 

 Here it usually extends as a fringe along the base of the slope (see Fig. 10). 

 In passing from Newcastle (5,562 ft.) up to 7,000 feet elevation, oak 

 increases in abundance, often covering whole hillsides at the higher 

 elevations From Rifle Gap to Rio Blanco Stage Station, the Little 

 Book Cliffs are in constant view on the left With increasing altitude 

 the appearance of these cliffs changes from a duller to a greener hue, 

 due to the greater abundance of oak chaparral. Intermixed with the 

 oak are bushes of mountain mahogany, which at this time of year are 

 in fruit, and the long plumose styles give them from a distance a silvery 

 color, standing out in pleasing contrast to the green mass of oak. 



Vegetation of Mancos shale. — Hills of Mancos shale are very desti- 

 tute of vegetation (Fig. 8). This shale is easily weathered, and on steep 

 slopes most of the vegetation that may get started is washed away. 

 Cercocarpus parvifolius and Amelanchier rubescens are the common 

 shrubs scattered here and there on the almost totally bare slopes. Erio- 



