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 Sazxifraga 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, 
Notholena sinuata, Notholena 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 wrighti, 
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 
Bowvardta 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 Cajions and some of their tributaries. 
The commonest herbaceous perennials of the flood-plains of the 
Upper Encinal are: 
Apocynum sp. Oenothera sp. 
Artemisia dracunculoides. Pentstemon torreyi. 
Asclepias tuberosa. Picradenia biennis. 
Carduus rothrockit. Pteris aquilina var. pubescens. 
Euphorbia crenulata. Rubus oligospermus. 
Geranium cespitosum. Senecio neomexicanus. 
Gomphocarpus hypoleucus. Solidago sparsiflora var. subcinerea. 
Gymnolomia multiflora. Sporobolus confusus. 
Monarda pectinata nutt. Thalictrum fendleri var. wrightit. 
Muhlenbergia sp. 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 
