The highest peak in the San Gabriel Mountains and the third in Southern California, this mountain has several unique features. Some of the botanical material has been covered in Devil's Backbone -North and South. Much of the forest is mixed evergreen.
In the summit area is a krummholz of lodgepole pine, Pinus murrayana. Here is the type locality for the rare Monardella cinerea and Eriogonum umbellatum var. minus, as well as for Ribes montigenum and Heuchera abramsii. The rare Eriogonum microthecum var. johnstonii is also present. Among the other noteworthy plants are Hulsea vestita, Caulanthus sp., Arabis platysperma, Minuartia nuttallii, Carex rossii, Calyptridium parryi, Galium parishii and Oreonana vestita, a talus plant.
Bighorn sheep, Ovis canadensis, lamb in the area.
Mount San Antonio is composed of a number of rock types; the summit and southwest slopes are quartz diorite, and the northern and eastern slopes are covered by pre-Cretaceous metamorphics, primarily Pelona schists. Excellent exposures of amphibolite dikes are found in Cattle Canyon, and pegmatite dikes, with 30-centimeter (12-inch) long potash feldspar crystals, are found in the area.
Integrity: There are several trails in the area which are well used. Smog from the Los Angeles Basin is damaging some of the vegetation.
Use: Research, educational, observational, light recreation.
Ref: Johnston, I. M. 1919. The Flora of the Pine Belt of the San Antonio Mountains of Southern Calif. Plant World Vol. 22, Nos. 3 and 4.
Inventory of California Natural Areas
Revision © 2008 Steven Louis Hartman