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- 
sonit, Cystopteris fragilis, Geranium cespitosum, Frasera speciosa, Thalic- 
trum fendlert var. wrightit, Galium asperrimum, Smilacina sessilifolia, 
Osmorhiza nuda, Disporum trachycarpum, Viola canadensis var. rydbergit, 
Ozxalis metcalfit, 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, Pseudotsuga, 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 
and Agrimonia, 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. ** Disporum trachycarpum. 
** Actea viridiflora. ** Draba helleriana. 
*** Agrimonia brittoniana var. occiden- *** Dugaldia hoopesii. 
talis. ** Epilobium novomexicanum. 
** Agrostis scabra var. subrepens. ** Hauisetum robustum. 
* Aralia humilis. *** Frasera speciosa. 
** Aspidium filiz-mas. *** Galium asperrimum. 
*** Bromus richardsonit. * Gentiana microcalyz. 
*** Carex sp. *** Geranium cespitosum. 
** Carex sp. ** Glyceria nervata. 
** Cerastium sericeum. ** Gyrostachys sp. 
* Delphinium scopulorum. ** Heracleum lanatum. 
