VEGETATION OF THE SANTA CATALINA MOUNTAINS. 31 



THE PINE FOREST. 



In the lowest stands of Pine Forest many of the dominant Encinal 

 forms are still to be found, but in no case do the evergreen oaks fail 

 to become more and more scattered in occurrence as the forest of pines 

 becomes more dense. Quercus emoryi and Pinus cembroides are scarcely 

 concerned in the overlapping of the Chaparral and Forest, as the former 

 reaches its upper limit at 6,300 feet, while the latter becomes confined 

 to the rocky non-forested or lightly forested ridges at about the same 

 elevation, although it persists as a rare shrub to an elevation of 7,800 

 feet. Arctostaphylos and Garry a are likewise of infrequent occurrence 

 in stands of forest. The oaks which are characteristic of the closed 

 forest are Quercus reticulata and Quercus hypoleuca. The former is com- 

 monly a low-branching shrub which often forms thickets on the steep 

 slopes of the highest peaks, where it extends upward to about 8,600 feet. 

 The latter oak is a shrub near its lower and upper limits at 6,000 and 

 8,500 feet respectively, but attains a height of 40 feet and a girth of 

 3 to 4 feet between 6,500 and 7,500 feet. Juniperus pachyphloea is of 

 occasional occurrence in the Forest up to 7,900 feet, and Arbutus 

 arizonica (Arizona madrona), at first infrequent, becomes common at 

 7,000 to 7,500 feet and reaches its upper limit at 7,800 to 8,000 feet. 



The composition of the Forest itself is extremely simple from its 

 lower limit around 6,000 feet to 7,500 feet, and above that elevation 

 is equally simple on southerly slopes up to the summit of Mount 

 Lemmon. Pinus chihuahuana reaches its limit at about 6,700 feet and 

 forms a very inconsiderable portion of the forest throughout the upper- 

 most 500 feet of its vertical range. Pseudotsuga mucronata begins to 

 occur on steep northerly slopes at 6,100 feet and Pinus strobiformis 

 (Mexican white pine) at 6,800 to 7,000 feet, but neither begins to 

 affect the composition of the Forest in general until higher elevations 

 are reached. At 6,000 feet the streamways and flood-plains are char- 

 acterized by several deciduous trees in addition to the pines themselves. 

 Platanus wrightii is near its upper limit at this elevation, Juglans 

 rupestris, Prunus virens, and Acer interior are of frequent occurrence, 

 while at 6,500 to 6,800 feet are found the lowest individuals of Quercus 

 submollis and Alnus acuminata. 



Throughout the Pine Forest are to be found a large number of her- 

 baceous perennials, a few of which occur in the Upper Encinal, the great 

 majority of which, however, accompany the closed stands of pine, with 

 additions and eliminations with increasing altitude. In addition to these 

 plants is another large group which is confined in occurrence to the near 

 proximity of streams and streamways; some of the members of the group 

 being thus restricted in occurrence at lower altitudes, while they are of 

 more general occurrence on heavily wooded slopes at higher elevations. 



In the clear park-like stretches of Pine Forest where no evergreen 

 oaks happen to occur, the most conspicuous plants on the forest floor 



