Eastward the parched Colorado Desert lies shimmering through the tremulous heat-waves. The fierce winds, asa they sweep upward to the pass, heap drifts of sand behind the ledges of rocks which jut out from the mountain’s base. The vegetation, answering the demands of its environment, is of plants fitted to endure heat and drought. Over the slopes are scattered cactuses and agaves; trees, green-barked and almost leafless, mark the courses of the dry torrential washes. Where in the frostless cañons a feeble stream trickles through the sands, palms lift their crowns.
The altitude of the desert which supports this Lower Sonoran flora is, at this point, about 500 feet above sea level, and the perpendicular distance to the summit of the mountain is, thereforee, some 10,300 feet. So steep is the acclivity that its slope seems no more than a third longer. In that short interval one passes from the vegetation of the Mexican Plateau to that of the circumpolar region. Instead of palms the gorges of the summit shelter long-enduring - perhaps perpetual - snows, about whose edges flourishes a true, though scanty, Arctic flora. Nowhere else are characteristic plants of the Arctic and Sonoran zones separated by so short an interval. Were it possible to clamber down the steep descent, one might in an hour pass from beside plants whose leaves must be nightly stiffened by frost, to those which never feel its touch.
This summit is, moreover, the point furthest south where alpine plants have been found in North America. Thus far at least, then, extended the refrigerating influence of the glacial period in the geological past. If it reached beyond, no mountains sufficiently high have preserved a record to our days, in plants left stranded, as the ice-cap retreated northward.
These northern and eastern faces of San Jacinto are too steep, rocky and arid, too much exposed to the heat and glare of the desert, to support other than the scanty shrubs and herbs that can cling in the crevices. Their zonal distribution is, at least, obscure. But on the opposite side the case is different. There the mountain falls by easier descents and sends out subsidiary ranges whose corrugated fold separate it from the Pacific. Coniferous forests clothe its slopes, enfolding meadows, with brooks and tiny lakelets. Here are conditions to encourage diversity of growths, and room for plant stratification to manifest itself. Mr. H. M. Hall* has traced out its disposition, and the causes which determine it.
In descending the mountain upon this side, one passes from the Arctic, successively through the Hudsonian, the Canadian and the Trans[i]tional life zones, to the Upper Sonoran; or, to take the pines as an index, leaves behind in turn the lumber-turg, the lodge-pole and the yellow pine (Pinus flexilis, P. Murrayana, and P. ponderosa), before reaching the great chaparral belt of the foothills.
As in all these southern mountains, the various zones are somewhat confused. In places they commingle, or they run promontories into one another’s territory, or intrude as “islands.” The familiar causes of such interpenetration are here supplemented by influences arising from the proximity of the desert, influences by which the disposition of the flora of the whole region bordering upon it are affected. It presents, therefore, a complicated problem, much more difficult than that on the desert side, where all the intermediate factors are practically eliminated.
* A Botanical Survey of San Jacinto Mountain. By Harvey Monroe Hall, University of California Publications [in] Botany 1, pp. 1-140. June, 1902.
We can learn about the visits to San Jacinto Mountain by Samuel Parish by a careful perusal of the publicatioin by Harvey Monroe Hall, because in the Introduction of that monograph, there is a discussion about several trips to San Jacinto Mountain by Samuel Parish in the 1880s and 1890s.
This essay by Samuel Parish is all but forgotton to historians who have written about San Jacinto Mountain, including John Robinson.