Flora of the Lake Hemet area of Garner Valley, San Jacinto Mountains
Bruce Watts and Tom Chester ![]()
Fig. 1. Top: View of the Lake Hemet area from along the Spitler Peak Trail looking southwest.
Bottom: View across Lake Hemet from its northwest end, looking east / southeast. Ericameria nauseosa var. oreophila, threadleaf common rabbitbrush, is in the foreground. The Desert Divide is the main skyline ridge, with the more distant Santa Rosa Mountains seen at the right where the Desert Divide ends near SR74. Note the people along the shoreline for scale.
Photos by Bruce Watts. Click on the pictures for versions showing a larger area.
Introduction
Shoreline, Aquatic, and Marsh Species Unique to Lake Hemet at San Jacinto Mountain
Procedure for Compiling the Checklist
Species Checklist
Notes on Some Species
Introduction Lake Hemet is located at the lowest end of Garner Valley, in the southern part of the San Jacinto Mountains, four miles east of Mountain Center, and about 20 miles east of the town of Hemet. The reservoir has 12 miles (19 km) of shoreline, which is at an elevation of 4340 feet (1322 m).
Lake Hemet is a reservoir constructed and owned by the Lake Hemet Water Company. The reservoir was built in order to supply water to develop the town of Hemet. It took four years to build the 122.5 foot tall dam, from 1891 to 1894. For sixteen years it was the tallest masonry dam in the world. After six feet of water poured over the top of the dam in January 1916, the dam was raised by 12.5 feet, to a height of 135 feet. Water has flowed over the dam several times since then, with only minor damage. (Source: Robinson and Risher, The San Jacinto Mountains, pp. 155 to 158; see also Historic Lake Hemet Dam)
For 37 years, the Water Company prohibited any public access to the lake, despite pressure from the public, and the Riverside County Board of Supervisors to allow it. Finally, they agreed in 1933 to open the lake to public use. (Robinson and Risher, pp. 158 to 159.) The eastern part of the lake is a public campground, with a day use fee of $25 and camping fees of $49 to $59 per night, entered from the Lake Hemet Campground Store area.
The Forest Service owns the land on the north shore of the lake, and has established a day use area for picnicking and fishing. An Adventure Pass ($5 / day) is required. The entrance to the Forest Service Land is along SR74 northwest of the Campground Store area, and southwest of Apple Canyon Road.
The flora of this area primarily comes from surveys by Bruce Watts of the Forest Service land, including the Lake Shore and the access road (see Fig. 4). The flora has been augmented by vouchers and iNaturalist observations.
The flora includes a separate checklist for species found in the area of the three bridges on SR74 of the streams that feed into the Lake. The northernmost bridge is signed "Antsell Rock Creek". The southernmost bridge is signed "South Fork San Jacinto River". The middle bridge is unsigned, since it drains a small unnamed area.
Most of the species in the flora are unrelated to the Lake, growing above the shoreline of the Lake and in the streams. However, it is of much interest to note the shoreline and aquatic species found in the Lake, since every one of them has had to be introduced into those areas since the Lake was filled 126 years ago. Many of those species presumably have arrived by birds or boats from areas outside of San Jacinto Mountain, since there are no permanent lakes here. We have only one ephemeral lake, Hidden Lake in Long Valley, which is at a much higher elevation, and has few species in common with Lake Hemet.
Reservoirs are a difficult place for shoreline and aquatic species to live, since the water levels change much more rapidly than they do in natural lakes. Plants may get established along the shoreline in years in which the lake level is low, and then become rapidly drowned by several feet of water when the lake fills up again from major storms; see the bottom right panel of Fig. 2. Plants may arrive one year, and be extirpated from the lake the next year. It might take several introductions before a species becomes established here. We don't know how long it takes for the lake to reach its equilibrium number of species, but we doubt it has already happened.
Shoreline, Aquatic, and Marsh Species Unique to Lake Hemet at San Jacinto Mountain The most interesting species unique to Lake Hemet at San Jacinto Mountain are ones that live in habitats created by Lake Hemet. That includes shoreline species, aquatic species, and ones that live in marshy areas. These species would not have lived at San Jacinto Mountain prior to the creation of Lake Hemet and Lake Fulmor, and the smaller ponds created by cattle ranchers.
There are 14 such species known only from Lake Hemet at San Jacinto, listed in Table 1. It is quite interesting that all but one of these species are native to southern California. Most of these species are known only from a single small area at Lake Hemet (different areas for different species), possibly indicating that they haven't reached their full potential distribution there.
The year that each of those species was first vouchered, or seen by us, is also given. The first year any of those species was vouchered was 1909, 15 years after the Lake was created. The next years were 1938, 1964, 1971, and 1987, each with a single species. Four species were vouchered in 1999, which was probably the first comprehensive collection event. We observed five additional species from 2013 to 2018 in our surveys, with one of them seen previously in 1973, but not identified correctly until 2020. That may, or may not, imply that those five species were introduced to this area in the last 20 years.
The species are listed in alphabetical order by Scientific Name in the tables in this section.
Table 1. Shoreline, Aquatic, and Marsh Species Known Only From Lake Hemet at San Jacinto Mountain
# Famil Scientific Name
Link goes to the Jepson eFlora(*)Common Name
Link goes to CalphotosYear first vouchered or seen 1 Apiac Berula erecta cutleaf water-parsnip V - 1964 2 Cheno Chenopodium rubrum red goosefoot V - 1999 3 Cyper Cyperus erythrorhizos redroot flatsedge V - 1999 4 Aster Eclipta prostrata false daisy V - 1999 5 Aster Euthamia occidentalis western goldenrod S - 2014 6 Arace Lemna turionifera turion duckweed S - 1973 7 Verbe Phyla nodiflora turkey tangle fogfruit S - 2013 8 Rosac Potentilla norvegica *Norwegian cinquefoil V - 1971 9 Brass Rorippa sphaerocarpa round-fruit yellow-cress V - 1999 10 Polyg Rumex fueginus golden dock V - 1909 11 Cyper Schoenoplectus californicus California tule S - 2015 12 Aster Solidago confinis southern goldenrod V - 1987 13 Aster Symphyotrichum subulatum var. parviflorum annual water-aster S - 2018 14 Viola Viola nephrophylla northern bog violet V - 1938 Five additional shoreline, aquatic, and marsh species are known only from Lake Hemet and perhaps from one or two nearby locations in the area, listed in Table 2.
Two of those species have vouchers from "upper end of Garner Valley". As far as we know, the upper (southeastern) end of Garner Valley doesn't have any habitats similar to that of Lake Hemet. We speculate that locality might actually be the lower end of Garner Valley, which is at the base of the mountains to the northwest. It seems quite possible that the collector might have assumed the Lake Hemet area was the "upper end" of Garner Valley. If so, those two species should be added to the 12 species in Table 1.
Two of the other species in Table 2 have vouchers from very nearby areas, from similar human-created habitat on a smaller scale, ponds at K Flat Meadow, the Quinn Flat / Kenworthy area, and Keen Camp. The pond at K Flat Meadow may now be gone, after the scouring rains of 2019 took out its dam.
The fifth species, Amaranthus californicus, has vouchers from a County Park just below the Forest lower boundary.
Three species are known only from Lake Hemet and Lake Fulmor, listed in Table 3. Lake Fulmor is also a reservoir, formed by damming of Hall Canyon when SR243 was built in 1948.
All but one of the species in Tables 2 and 3 are also native.
Table 2. Shoreline, Aquatic, and Marsh Species Known Only From Lake Hemet and Perhaps One or Two Nearby Locations at San Jacinto Mountain
# Famil Scientific Name
Link goes to the Jepson eFlora(*)Common Name
Link goes to CalphotosNotes 1 Amara Amaranthus californicus California amaranth Only other is SR243 just below Forest boundary 2 Poace Crypsis schoenoides *swamp grass Only other location is "upper end Garner Valley" 3 Poace Leptochloa fusca ssp. uninervia Mexican sprangletop Only other location is "upper end Garner Valley" 4 Poace Paspalum distichum knot grass Voucher from Keen Camp 5 Verbe Verbena bracteata bracted verbena Voucher from K Flat; seen at Quinn Flat pond Table 3. Shoreline, Aquatic, and Marsh Species Known Only From Lake Hemet and Lake Fulmor at San Jacinto Mountain
Some of our favorite species listed in Tables 1 through 3 are shown in Fig. 3.
Procedure for Compiling the Checklist This checklist was compiled from a number of visits to the publicly-accessible area of Lake Hemet, including the bridges on SR74 over the eastern tributaries to the lake; from vouchers; and from iNaturalist observations.
Fig. 4 shows the Lake Hemet area, along with the surveyed portions.
Fig. 4. The Lake Hemet Area. The Survey Area along the north edge of the Lake is in the National Forest, accessible by foot or vehicle. The eastern area is a campground with a day use fee of $25 per day. The dam is at lower left, not publicly accessible. Three bridges over the eastern tributaries that were also surveyed for this Flora are circled at right. Click on the map for larger version.
Bruce surveyed the Lake Hemet area shown in Fig. 4 with the red lines on 31 July 2020, 3, 4, and 5 August 2020. He surveyed the bridge areas on 7 and 9 August 2020.
The bridge areas were also surveyed by Bruce, Tom, Nancy Accola and Don Rideout on 19 and 23 September 2019.
After a preliminary checklist was created from the above surveys, Bruce went back through his pictures from his many trips in prior years, and found additional species for the flora.
There were 210 observed species from the above.
On 16 August 2020, a search of iNaturalist observations by Tom found four additional species
On 19 August 2020, Tom searched vouchers for additional species. Vouchers were first searched in a rectangle that covered the Lake Hemet area, and then the localities were reviewed, keeping only those vouchers that clearly indicated they were from the Lake, or the Bridge area. That resulted in accepting 149 vouchers, which added 30 species to the Flora.
The Checklist below contains a total of 245 taxa the above sources.
See Notes on Some Species for some species that were excluded from this flora.
Species Checklist The following gives some basic information about this checklist.
See:
- Notes on the Scientific Names Used At This Site and
- Information about the links from the Scientific Name and Common Name.
For this flora, the monkeyflower scientific names have been updated to ones used in the Jepson eFlora revision of 2018.
An asterisk before the common name indicates a non-native species.
The last two columns indicate whether a species was found in the Lake Hemet Area (column title LH), or in the three bridges area (column title Br). In those columns, an x indicates we observed it; a P indicates we observed it and we think it was planted; a W indicates it was only observed once, and is likely a Waif. Species with iN in those columns are ones we haven't seen, but were recorded at iNaturalist. Species with V in those columns are ones we haven't seen, but are vouchered from this area. Some of those vouchered species may not actually be from the Lake Hemet area, since the voucher locality may just be the nearest landmark.
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Notes on Some Species Centaurea solstitialis, yellow star thistle. There is a voucher of it from 1959 from one of the bridges over SR74, but no one else has ever seen it anywhere in the San Jacinto Mountains. The collector also collected from lower elevations in Riverside County on the same day, where it has been collected by others. It is thus possible he gave the wrong locality for this collection. We have therefore rejected this species from the list.
Cryptantha corollata, Coast Range cryptantha. A specimen was collected by A. C. Sanders and Mitch Provance on 26 September 1999 from the "north shore day use area". We suspect that specimen is a depauperate C. muricata, since the most significant difference between those two species is the number of nutlets. C. corollata is otherwise known only from the Riverside / Hemet / Temecula Valley at lower elevation. But we'll look for this in the future, to see if there is indeed a population of this species here.
Ribes roezlii, Sierra gooseberry. There is an iNat observation of this species with a location that plots in the water area. Tom surveyed the area near that voucher location without finding any plants of that species. Bruce has only seen that species to the west, in the Keen Camp Summit area. We have removed this species from the list until a good location for it here is known.
Zeltnera exaltata, desert centaury. There are three vouchers of this species, all from the same collection event in 1935. However, we suspect these are just the four-petaled form of Zeltnera venusta, which is not infrequently found amidst a much larger number of plants with the usual five petals. Bruce has seen such plants twice in nearby areas, at K Flat and Apple Canyon Creek. As far as we know, there are no populations of Zeltnera exaltata in this area.
We thank Nancy Accola and Don Rideout for their help in the bridge surveys on 19 and 23 September 2019, and Wayne Armstrong for the determination of Lemna turionifera, turion duckweed.
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Copyright © 2020 by Bruce Watts and Tom Chester
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Comments and feedback: Tom Chester
Last update: 14 September 2020