Flora of Laguna Meadow Area, Laguna Mountains, San Diego County
Introduction
This checklist was made solely from vouchers, except for the addition of one species incidentally noted on a field trip on 10 October 2017.
On that field trip I was looking forward to seeing some of the species at the edge of the water of Big Laguna Lake, or in areas that had been previously covered by water. However, when we got to the Lake, we discovered that the entire area had been trashed by the large number of cows there. The wet area plants had been eaten down to stubs, and the entire area had been churned by zillions of hoofprints of the cattle. See, for example, this picture from just above the dam, showing some of the culprits at upper left. Most of the cows were in the water of the Lake, or at the margins of the Lake, not visible in the linked picture. The linked picture only shows the trampling in this area, since it is not right at the lake margin. Unfortunately, I failed to take a picture of the depressing scene at the lake margin, due to my disappointment at the time.
Although grazing has its place, particularly in controlling the growth of non-native annual grasses, in this case the grazing is totally out of place, with no beneficial effects. The cattle are mostly eating the lush riparian area plants, and ignoring the vast fields of non-native annual grasses in the dry margins of the lake. It would seem a good use of money for conservation organizations to buy out the grazing rights here, and get the cattle out of the lake area.
With such heavy pressure from extreme cattle grazing, along with the large fields of non-native weeds we observed in the meadow, one wonders how long the native plants and animals can survive. A butterfly, the Laguna Mountains Skipper, dependent on its rare host plant Horkelia clevelandii found here, has apparently been extirpated from this area, its type locality, due to the heavy grazing:
Habitat destruction and degradation from overgrazing and trampling by cattle are considered to be the reasons for the decline of H. clevelandii (62 FR 2314); however, this plant has not been federally or state listed. Grazing by cattle in the Laguna Mountains and near Mount Palomar has been shown to cause direct mortality of larvae and eggs by trampling and consumption of H. clevelandii (62 FR 2314, Black and Vaughan 2005). Related changes in hydrology, invasion of exotic species, and forest encroachment caused by cattle grazing also affect the host plant....
Lack of recent (1999 to present day) sightings on Laguna Mountain at areas with former known sighting concentrations and with the highest density of Horkelia clevelandii and Laguna Mountains skipper suggest that the entire Laguna Mountain range may have become depopulated since the time of listing (Anderson, pers. comm. Dec. 2006). Individual Laguna Mountains skippers have not been detected on Laguna Mountain since 1999 (Pratt 2006), and any remaining populations may not be resilient enough to survive into the foreseeable future under current conditions. Laguna Mountain constituted over half of the Laguna Mountains skipper’s former range (Figure 1). Loss of occupancy in this area may reflect a significant loss of genetic diversity for the skipper, and alter its long-term ability to adapt to changing environmental conditions and stochastic eventsevents. However, not all suitable habitat has been surveyed, and low populations are difficult to detect (Anderson, pers. comm. Dec. 2006). At this time, insufficient evidence exists to conclude that suitable habitat in the Laguna Mountains no longer supports an extant population, and presumption of complete extirpation would be premature at this time.
Laguna Mountains Skipper (Pyrgus ruralis lagunae)
5-Year Review: Summary and Evaluation
U.S. Fish and Wildlife Service
Carlsbad Fish and Wildlife Office
Carlsbad, California
September 2007
Vouchers
Vouchers were searched on 8 October 2017 at Consortium of California Herbaria. A geographic coordinate search, for vouchers with coordinates, was made for the region of 32.86 to 32.91° north latitude and -116.48 to -116.44° east longitude. No separate search was made for non-georeferenced vouchers.
The search yielded a total of 1653 vouchers. Fig. 1 shows the locations of the retrieved vouchers.
Fig. 1. Locations of all 1653 retrieved vouchers (black dots). Laguna Meadow is outlined in blue. The "Laguna Meadow Area" is here defined by the locations of the black dots.
The vast majority of vouchers are outside Laguna Meadow itself. Since a checklist based just on Laguna Meadow vouchers would be very incomplete, I've compiled the checklist here using vouchers from the entire area shown in Fig. 1, which I hereby take as the "Laguna Meadow Area". Since this is a much bigger area than just Laguna Meadow itself, this checklist should not be construed as a checklist for just Laguna Meadow.
Vouchers with a locality of Oasis Spring were tossed, since that is a very different habitat than most of the rest of this area. If it had been easy to do so, I would have tried to toss other vouchers taken from the escarpment to the east of the flattish area. But unfortunately the vagueness of the localities for many vouchers made that a nearly impossible task, so I was only able to toss the Oasis Spring vouchers since that is a definitive location.
A checklist was then made from the remaining vouchers. 15 taxa were rejected from that checklist, since I judged them to be either misdetermined, or incorrectly georeferenced; see Table 1. Five of these taxa are Baja California species, collected by Marcus Jones from “The Laguna, Laguna Mountains”, undoubtedly from the Sierra de la Laguna mountain range in Baja, not from the Laguna Mountains in San Diego County.
The final list contains 436 unique taxa from the vouchers, augmented by one species (Erigeron canadensis) we incidentally noted on a field trip on 10 October 2017.
Table 1. Taxa Rejected from the Checklist
| Taxon | Reason for rejection |
|---|---|
| Allium bisceptrum | Probable misdetermination since it is way out of range. The Jepson Manual (JM) regions are: CaRH, SNH, GB |
| Arracacia brandegei var. sylvatica | Error in georeferencing; this is a Baja California taxon (a collection from “The Laguna, Laguna Mountains” with no collector info; probably from Marcus Jones) |
| Astragalus pomonensis | Probable misdetermination of the very similar A. douglasii. A. pomonensis is mostly a low elevation taxon |
| Borreria lagunensis | Error in georeferencing; this is a Baja California taxon (Marcus Jones collection from “The Laguna, Laguna Mountains”) |
| Encelia californica | Error in georeferencing; this is probably from “Laguna Hills” in Orange County |
| Horkelia bolanderi | Probable misdetermination of H. clevelandii, which is also known as H. bolanderi ssp. clevelandii. The JM region for H. bolanderi is only NcoRI. |
| Lechea tripetala | Error in georeferencing; this is a Baja California taxon (Marcus Jones collection from “The Laguna, Laguna Mountains”) |
| Lithophragma heterophyllum | Probable misdetermination: JM regions: NCoRO, s NCoRI (Solano, Napa cos.), n SNH (Calaveras Co.), SnFrB, ScoR |
| Plectritis macrocera | Probable misdetermination; the dupe of the voucher is the expected P. ciliosa |
| Ptelea aptera | Error in georeferencing; this is a Baja California taxon |
| Quercus Xmacdonaldii | Typo in determination, since the voucher annotation says Q. Xacutidens |
| Symphoricarpos mollis | A historical misdetermination: the Laguna plants are all S. albus |
| Trifolium depauperatum var. amplectens | Probable misdetermination: JM regions GV, SnFrB, ScoR |
| Verbena carolina | Error in georeferencing; this is a Baja California taxon (Marcus Jones collection from “The Laguna, Laguna Mountains”) |
| Verbesina pustulata | Error in georeferencing; this is a Baja California taxon (Marcus Jones collection from “The Laguna, Laguna Mountains”) |
Checklist
See:
- Notes on the Scientific Names Used At This Site and
- Information about the order in which the species are presented, and the links from the Scientific Name and Common Name.
An asterisk before the common name indicates a non-native species.
The family name is abbreviated to the first three characters in order to save space in the table rows.
The column #V gives the number of vouchers for this area. The single species no voucher, Erigeron canadensis, was incidentally noted on a field trip on 10 October 2017 where we did not record the species we saw.
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