Flora of S2 Mile Marker 0 to 4.6, San Diego County This section of road is in the upper part of the Lake Henshaw basin, just above Buena Vista Creek following the north base of the Volcan Mountains, about midway between the spillway of Lake Henshaw and Ranchita, at elevations of 2836 to 3300 feet. Some sections are very similar to the Lake Henshaw grassland, and some sections are shrublands.
Mile Marker 0.0 for San Diego County Road S2 is at the junction with SR79 east of Lake Henshaw and south of Warner Springs, elevation 2836 feet. The road steadily increases in elevation to 3300 feet at Mile Marker 4.6 is at the junction with S22, Montezuma Valley Road.
We often stop along this section of S2 on our way to the Borrego Desert, and finally decided we might as well compile a list of some of the species we incidentally observed on our stops. To make the list more complete, we also added species from vouchers, which may or may not be present along the roadside.
Perhaps the most interesting taxon in the list before is the Warner Springs Lessingia, Lessingia glandulifera var. tomentosa, which only lives in the Lake Henshaw immediate drainage area, but which is abundant in this stretch of the road. At mile 0.4, it is intermixed with var. glandulifera, but then the roadside is solid var. tomentosa up to mile 4.55, where it is again mixed with var. glandulifera. We've stopped here numerous times to show fellow botanists var. tomentosa.
Three species, and probably a fourth, appear to be planted here. On the south side of S2, immediately west of the junction with S22, there is a line of Fraxinus velutina trees as well as at least one Pinus jeffreyi and one Hesperocyparis stephensonii. The last two species are considerably out of range in this area, and the habitat here doesn't look like typical Fraxinus velutina habitat. The Pinus coulteri have probably been planted along the roadside as well, but it is native to this general area.
The checklist was compiled from a search of the Consortium of California Herbaria on 15 August 2014, as well as from scattered stops along the road in 2005, 2013, 2014 and 2015. We specifically botanized the road at eight stops on 8 April 2015, when the area was in peak bloom, in order to make the flora more complete. See Photos from Fred Melgert from that survey.
We've made many more stops along here in other years, and we may gradually add observations from those stops as we come across those data.
One of the first times we stopped along this road was in October 2005, when we observed An April Bloom In October! here.
The vouchers came from a geographic search for georeferenced vouchers between 33.22 and 33.25° latitude, and -116.68 to -116.60° longitude. The localities of the vouchers were reviewed, and ones not clearly from the vicinity of S2 were tossed. A Parish voucher for Geraea viscida from the year 1880 was tossed, even though the locality says At Warner's Ranch and other elevated places in San Diego Co. since all other San Diego County vouchers are from southeast County.
The checklist as of 11 April 2015 contains 115 taxa from our observations, and an additional 105 taxa from vouchers from this area. Those voucher taxa may or may not be present along the road.
An asterisk before the common name indicates a taxon not-native to California.
The column #V gives the number of vouchers for each species. Note that some of these vouchers might not have been taken from the immediate vicinity of S2.
The column Mile gives the mile marker for the first location at which we observed a given taxon. If the column contains an x, we have observed that taxon somewhere in this section, but do not have a precise location. If the column contains a V followed by a mile marker, it was vouchered at that mile marker.
You can easily locate a given mile marker by starting at the junction with SR79 and resetting your trip odometer to zero. Your trip odometer will then correspond to the mile markers.
Version for printing, without lines and other text on this page: html (6 pages) or pdf Clickbook booklet (2 double-sided pages). (See printing instructions for an explanation of these options)
Voucher data provided by the participants of the Consortium of California Herbaria (ucjeps.berkeley.edu/consortium/).
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Copyright © 2014-2015 by Tom Chester, James Dillane, Kate Harper, Adrienne Ballwey, Carla Hoegen, Fred Melgert, Keir Morse, Jim Roberts, and Nancy Accola
Permission is freely granted to reproduce any or all of this page as long as credit is given to us at this source:
http://tchester.org/plants/floras/pr/S2_mile_0_to_5.html
Comments and feedback: Tom Chester
Last update: 11 April 2015