i6 7 ] 



FLORA OF BOULDER, COLORADO 



19 



P. argophylla 

 Geranium Fremontii 

 Linum Lewisii 

 Tithymalus philorus 

 Nuttallia multiflora 

 N. stricta 



Epilobium paniculatum 

 Gayophytum intermedium 

 Meriolix serrulata 

 Gaura parviflora 

 Gilia Candida 

 G. pinnatifida 

 G. sinuata 

 Collomia linearis 

 Phacelia heterophylla 

 Oreocarya virgata 

 Mertensia linearis 

 M. lanceolata 

 Pentstemon unilateralis 

 P. secundiflorus 



P. gracilis 

 P. humilis 



Castilleja linariaefolia 

 Campanula petiolata 

 Gutierrezia longi folia 

 G. scoparia 

 Chrysopsis resinolens 

 Solidago pallida 

 Townsendia grandifiora 

 Rudbeckia flava 

 Ratibida columnaris 

 Helianthus subrhomboideus 

 Gaillardia aristata 

 Artemisia dracunculoides 

 A. Forwoodii 

 A. frigida 

 A. Brittonii 

 Senecio Plattensis 

 S. Nelsonii 

 S. Fendleri 



b. Spinosae. The vegetation of the cactus mesa con- 

 sists of a few species of cacti, of the prickly Ceanothus Fend- 

 leri, and a few other xerophytic plants and undershrubs. The 

 principal cacti are : 



Echinocereus viridiflorus O. polyacantha 

 Opuntia mesacantha O. fragilis 



O. rhodantha O. Greenei 



c. Ensiformes. The best example of the Yucca mesa 

 occurs near the entrance of Bear Canon. There the ground is 

 practically denuded, and only sparse clumps of Yuccas and 



