VEGETATION OF THE SANTA CATALINA MOUNTAINS. 29 



be very uncertain, Laphamia lemmoni is found, a small composite 

 known only from the Encinal region and only from this habitat. In 

 crevices more favorably situated with respect to moisture may be found 

 Heuchera sanguinea, and on north slopes at 6,000 feet, in moist crevices, 

 may be found the lowest colonies of Saxifraga eriophora, a plant which 

 occurs infrequently up to the summit of the mountain. 



Beds of Selaginella rupincola are still to be found at 6,000 feet and 

 the several species of drought-resistant ferns, which are confined to the 

 shade of rocks at lower elevations, are common on the floor of the heavy 

 stands of Pinus cembroides, or grow among the boulders in more open 

 situations. Among these the most common are : Cheilanthes fendleri, 

 Notholcena sinuata, Notholcena ferruginea, and Gymnopteris hispida. None 

 of these species extend upward into the Forest region (see plate 14) . 



The drier flood-plains and arroyos of the Upper Encinal are charac- 

 terized by the same oaks and evergreen conifers that occur on the 

 adjacent slopes, while the moister streamways bear a number of decidu- 

 ous trees and shrubs, notably Juglans rupestris and Platanus wrightii, 

 extending upward from streamways at lower elevations, and Prunus 

 virens, Rhamnus ursina, Rhus trilobata, Robinia neomexicana, and Rhus 

 elegantula. Less frequent are Ceanothus fendleri, Berberis wilcoxii, and 

 Bouvardia triphylla, and Vitis arizonica is still common. Pinus chihua- 

 huana is not infrequent along the drier arroyos at the lower edge of its 

 range, and Cupressus arizonica is found along the streams and on the 

 lower slopes of Sabino and Bear Canons and some of their tributaries. 



The commonest herbaceous perennials of the flood-plains of the 

 Upper Encinal are: 



Apocynum sp. 

 Artemisia dracunculoides. 

 Asclepias tuberosa. 

 Carduus rothrockii. 

 Euphorbia crenulata. 

 Geranium caespitosum. 

 Gomphocarpus hypoleucus. 

 Gymnolornia multiflora. 

 Monarda pectinata nutt. 

 Muhlenbergia sp. 



Oenothera sp. 



Pentstemon torreyi. 



Picradenia biennis. 



Pteris aquilina var. pubescens. 



Rubus oligospermus. 



Scnecio neomexicanus. 



Solidago sparsiflora var. subcinerea. 



Sporobolus confusus. 



Thalidrum fendleri var. wrightii. 



Zauschneria californica. 



THE FOREST REGION. 



One of the most striking changes encountered in the vegetational 

 gradient of the Santa Catalinas is that from the closed and relatively 

 low Encinal to the open forest of Pinus arizonica, with trees 50 to 60 

 feet in height. This pine, the Arizona yellow pine, is closely related 

 to Pinus ponderosa, the western yellow pine, and is the common tree 

 of the forested altitudes of the mountain, extending upward on south- 

 erly slopes to the summit of Mount Lemmon. The lowest stands of 

 pine which possess sufficient density to be regarded as forest occur on 

 northerly slopes at 5,800 to 6,000 feet, or on southerly slopes at 6,000 

 to 6,400 feet, the limits depending in each particular locality upon the 



