Flora of Santa Rosa Mountains


Flora of the Santa Rosa Mountains From Vouchers (546 taxa).

Jan G. Zabriskie's 1979 Plants of Deep Canyon, Santa Rosa Mountains, updated by Tom Chester, 2006 (607 taxa)

Overview of Flora of Santa Rosa Mountains

Fig. 1. Area map showing the location of the San Jacinto and Santa Rosa Mountains. The purple line outlines the perimeter of the mountains and also divides them into their separate ranges. The dotted purple line is an alternate boundary line. The black line gives the boundaries of Anza-Borrego Desert State Park. The green line outlines the Pine Belt of San Jacinto Mountain. Red lines outline two individually-labeled areas with floras. Blue lines outline trails, most of which have plant trail guides produced for them.

The San Jacinto Mountains and Santa Rosa Mountains are in many ways a single geographic entity, bounded by the San Andreas Fault on the north and northeast, and the San Jacinto Fault on the southwest. In the above map, the outermost purple line outlines the perimeter of the mountains.

Although the boundary between the two mountain ranges is somewhat arbitrary, one major drainage, Palm Canyon, and one minor drainage, Horse Canyon, provide a fairly natural separation. This boundary is shown by the north-south purple line in the middle of the map that follows Palm Canyon, and is described below.

In the north, the Palm Canyon drainage clearly defines the major mass of San Jacinto Mountain. Heading west from any point at the bottom of Palm Canyon, one clearly is ascending San Jacinto Mountain. Heading east leads to very different territory, a plateau of elevation only ~4000 feet.

In the middle, the southwestern head of Palm Canyon is roughly aligned with the top of Horse Canyon, both at the western edge of Vandeventer Flat. This area forms a natural saddle to separate the two Ranges in this area. This boundary also nicely coincides with the edge of the San Jacinto Mountain pine belt.

In the south, Horse Canyon joins Coyote Canyon, which follows the southern branch of the San Jacinto Fault, and separates the Santa Rosa Mountains from the Hot Springs / San Ysidro Mountains to the south. However, since there are two strands of the San Jacinto Fault here, it is arbitrary as to which strand is the best boundary. The northerly strand follows the dotted purple line shown above, which would probably be just as good a choice for the boundary.

No one has ever produced a flora of either the entire San Jacinto Mountains, the entire Santa Rosa Mountains, or their union. The only floras for any part of this region that I know of are:

  • Harvey Monroe Hall's 1902 Flora of the Pine Belt of the San Jacinto Mountains (see Flora of San Jacinto Mountain). The boundaries of his flora are shown in purple above, labeled Pine Belt.

  • Jan G. Zabriskie's 1979 Plants of Deep Canyon, Santa Rosa Mountains. The boundaries of his flora are shown in red above, labeled Deep Canyon.

  • Ken Berg's 1982 Hall Canyon Annotated Floristic List (see current Hall Canyon Plant Species List). The boundaries of this small area are shown in red above, labeled Hall Canyon.

    If you know of other floras for any part of these Mountains, please let me know.

    I have taken two steps toward producing a Flora of the Santa Rosa Mountains. First, I've collected online vouchers for the Santa Rosa Mountains, as defined above, above 2000 feet elevation, and updated them to the Jepson Manual names and species circumscriptions as much as possible. The resulting Flora of the Santa Rosa Mountains From Vouchers contains 546 taxa.

    Second, I've updated Zabriskie's Plants of Deep Canyon in the same way, and placed the list of 607 taxa online.

    I plan to combine the following two floras, along with my Plant Trail Guides For Trails in the Santa Rosa Mountains, to create a single flora for this area. Each of these two floras contain a significant number of species not found in the other, and I have found additional species not in either flora on the trails.

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    Copyright © 2006 by Tom Chester.
    Permission is freely granted to reproduce any or all of this page as long as credit is given to me at this source:
    Comments and feedback: Tom Chester
    Updated 1 December 2006.