20 UNIVERSITY OF MISSOURI STUDIES [l68 



bunch-grasses occupy the ground. The two species of im- 

 portance are Yucca glauca and Eriocoma cuspidata. 



d. Sylvestres. A good example of the wooded mesa 

 Hes immediately back of the Chautauqua grounds. There the 

 bull pine has descended from the foot-hills and taken posses- 

 sion of the mesa. Besides the bull pine, Pinus scopulorum, 

 the low juniper, Juniperus Sibirica, is of rare occurrence. 

 Of herbs the most noteworthy is Arnica pednncnlata, which 

 is frequent under the pines. I found also only there Centun- 

 culus minimus, perhaps the only known station of this plant in 

 Colorado, since it is not included in Rydberg's Flora of Colo- 

 rado. It is growing with Linaria Canadensis, which is like- 

 wise an eastern plant. 



e. Arbustales. The brush mesa assumes various forms. 

 Ordinarily some one species is in control. Occasionally it con- 

 sists of various haws, as at the entrance of Gregory Canon, 

 or of a thicket of juneberries, wax-currants, and skunk-bushes. 

 South of Bluebell Canon is a mesa covered with the peculiar 

 mountain mahogany. Wild cherries and plums are frequent, 

 and the hackberry occasional in these shrubby thickets. The 

 principal species are: 



Celtis reticulata C. erythropoda 



Ribes pumilum Prunus Americana 



R. longifolium P. melanocarpa 



Oreobatus deliciosus Toxicodendron Rydbergii 



Batidaea laetissima Schmaltzia trilobata 



Cercocarpus parvi folium Ceanothus Fendleri 



Rosa Sayi C. mollissimus 



Amelanchier oreophila C. subsericeus 



Crataegus occidentalis Symphoricarpos occidentalis 

 C. Coloradensis 



