VEGETATION OF THE SANTA CATALINA MOUNTAINS. 



35 



philus, Ribes pinetorum, and Rubus neomexicanus. The trifoliate 

 maple, Acer glabrum, also occurs locally on the north slopes of Mount 

 Lemmon. The poverty in the stand of herbaceous species on the floor 

 of the Fir Forest is contrasted with the large number of species to be 

 found, which is probably not so great, however, as the number charac- 

 teristic of the open Pine Forest. Most common are: Bromus richard- 

 sonii, Cystopterisfragilis, Geranium ccespitosum, Frasera speciosa, Thalic- 

 trum fendleri var. wrightii, Galium asperrimum, Smilacina sessilifolia, 

 Osmorhiza nuda, Disporum trachycarpum, Viola canadensis var. rydbergii, 

 Oxalis metcalfii, Fragaria ovalis, Trifolium rusbyi, and Draba helleriana. 

 On Abies the parasitic Phoradendron bolleanum is not infrequent. 



The banks of constant and intermittent streams and the narrow 

 flood-plains of the Fir Forest region form a series of habitats with 

 closely similar physical conditions and with nearly identical vegetation. 

 In them are to be found a greater abundance and variety of trees and 

 shrubs than occur in topographically analogous habitats at lower ele- 

 vations. Abies, Pscudotsuga, Pinus strobiformis, and even Pinus 

 arizonica occur in this habitat. Its commonest woody plants, however, 

 are those which do not occur in other situations, as Alnus acuminata, 

 Acer interior, Acer brachypterum, Salix scouleriana, Salix exigua, Salix 

 taxifolia, Sorbus dumosa, Cornus stolonifera var. riparia, Jamesia ameri- 

 cana, Sambucus vestita, Symphoricarpos oreophilus, Rubus arizonicus, 

 Ribes pinetorum, and Salix sp. 



In this same series of habitats, which are the most elevated of the 

 moist habitats of the mountain, is the most dense stand of herbaceous 

 vegetation that occurs on the Santa Catalinas. This vegetation is rich 

 in species and varies in its make-up from place to place according to 

 the amount of soil moisture present and according to the openness or 

 shade. In the following list are given the characteristic plants of these 

 situations. The two species of Mimulus are the only plants invariably 

 confined to the immediate proximity of water. Such plants as Dugaldia 

 a,udAgrimonia, on the other hand, are found only in the unshaded flood- 

 plains. A comparison of this list with that just given for the floor of the 

 Fir Forest will show that the latter habitat has few distinctive species. 



Characteristic Herbaceous Plants of Flood-Plains, Stream Banks, and Lower Slopes in the 



Fir Forest. 



** 



* Aconitum columbianum. 

 Aclcea viridiflora. 



*** Agrimonia brittoniana var. occiden- 



talis. 

 ** Agrostis scabra var. subrepens. 



* Aralia humilis. 



** Aspidium filix-mas. 

 *** Bromus richardsonii. 

 *** Car ex sp. 

 Car ex sp. 



** Cerastium sericeum. 



* Delphinium scopulorum. 



** 



** Disporum trachycarpum. 



** Draba helleriana. 

 *** Dugaldia hoopesii. 



** Epilobium novomexicanum. 



** Equisetum robustum. 

 *** Frasera speciosa. 

 *** Galium asperrimum. 

 * Gentiana microcalyx. 

 *** Geranium ccespitosum. 



** Glyceria nervata. 



** Gyrostachys sp. 



** Heracleum lanatum. 



