Introduction Flora of north side of Mt. Waterman above SR2, San Gabriel Mountains
Composition of Checklist
Note on Phacelia imbricata
Diversity of Species here
Lupinus breweri
The FloraFig. 1. The north side of Mt. Waterman about SR2, seen in a Google Earth view to a bit west of directly south, showing the route surveyed on 24 June 2015. Note that the route, known as the Mt. Waterman Loop, is almost entirely along ridgelines, crossing the main drainage at only a single point. The Angeles Crest Highway, SR2, is the yellow line going mostly east-west 1/3 of the way up from the bottom. Twin Peaks are seen just above our route to the left of middle. GPS locations of Lupinus breweri, a species known only from this area in the San Gabriel Mountains, are marked with numbered flags. The bare scraped areas are the ski slopes.
Click on the picture for a larger version.Introduction
For photographs of many of the plants observed on the 24 June 2015 field survey, see the Photo Gallery by Michael Charters.
Composition of Checklist
This checklist contains species found in a search of vouchers from the Consortium of California Herbaria on 22 June 2015, and from the following surveys of this area:
- Michael Charters in June 2008; see his Photo Gallery from that trip.
- Tom Chester and Michael Charters on 24 June 2015
The voucher search was done by searching for vouchers with Waterman in the locality name. Those vouchers were then manually reviewed to exclude ones not taken on the north side of Mt. Waterman. Vouchers from areas below the Angeles Crest Highway (SR2), such as the Burkhart Trail, were also excluded.
Five taxa in the remaining vouchers were excluded as being misdeterminations or not actually taken from this area: Calochortus kennedyi, Ericameria parryi, Eriogonum umbellatum var. canifolium, Heuchera abramsii, and Triteleia dudleyi.
Note on Phacelia imbricata
One vouchered taxon, Phacelia imbricata ssp. patula, was changed to just the species after we found that the plants here are actually intermediates between ssp. patula and ssp. imbricata. One plant we examined had the narrow calyx lobes of ssp. patula, but the leaf segments greater than 7 and glandular calyx lobes of ssp. imbricata.
Heckard, in his beautiful and thorough 1960 Monograph on Taxonomic Studies in the Phacelia Magellanica Polyploid Complex (UC Pub. Bot. 32:1-126), noted three groups of intergrades involving ssp. patula. He recognized that most of the plants in the San Gabriel Mountains between 3000 and 7000 feet were intergrades that he placed in what he called Group I (of three such groups in southern California), and wrote:
in all three groups the narrow calyx lobe is present and is important owing to the association of this character as a regular feature (and key character) of ssp. patula. The plants of group I are largely like those of ssp. imbricata in other characteristics. p. 43.We feel it is misleading to call these plants ssp. patula when they are actually intermediates between the two subspecies, and hence we just call these plants the species name, without any subspecies.
Diversity of Species here
It was apparent to us during our 24 June 2015 survey that a number of species that are found in the surrounding area do not seem to be present here. In addition, a number of species were found only at a single location, and so just barely got into the flora. For example, we found only a single Cryptantha species, and that was only at one spot!
This lack of species diversity appears to be due to a variety of reasons. Among them are:
- This area is a solid north- / northeast-facing slope, without any significant portions that have a southern exposure within it. This excludes species found on south-facing slopes, such as Saltugilia splendens and Castilleja applegatei.
- North-facing slopes in the pine forest are typically depauperate in species, with the trees excluding other species by their shade and pine duff.
- The elevation of this area is quite high, above 6800 feet, which excludes a lot of species found only at lower elevations.
- This area is quite dry. We encountered only two moist areas, a drainage near the Angeles Crest Highway that was not very moist on 24 June 2015, and a wonderful moist meadowy area just west of the water reservoir near the top. Other than those areas, the drainages are dry, not at all like the snow-melt gullies found below Mt. Baden-Powell, for example.
Note however, that our survey almost entirely avoided the length of the main drainage in this area. Undoubtedly more riparian species would be added to the flora with a targeted survey of that drainage.
Lupinus breweri
Interestingly, this is the only location of Lupinus breweri in the San Gabriel Mountains, a matted species confined to the open gravelly areas ("balds") in the ridgelines near the top, accompanied by mats of Eriogonum wrightii var. subscaposum. Furthermore, as far as we know, all locations of this species are within a maximum extent of just one mile, with our recorded locations a maximum of 0.9 miles apart (see locations plotted in Fig. 1).
We do not know for sure, but it is possible that this species has the smallest extent of any higher-elevation species in the San Gabriel Mountains. We know of one other native species at lower elevation, Monardella breweri var. glandulifera, has a similar small range, confined to Browns Flat above Glendora. Lupinus stiversii has a smaller extent, found only in the immediate vicinity of Mt. Lowe Campground, but it almost surely is not native to the San Gabriel Mountains.
It is less than clear why this would be the only location of L. breweri in the San Gabriel Mountains, since there are similar bald areas in many other places in the San Gabriels with tons of Eriogonum wrightii var. subscaposum. Perhaps the presence of L. breweri here has something to do with the very unusual large flattish area at the top of Mt. Waterman.
We examined closely some plants of L. breweri and they are clearly var. grandiflorus, since the keel is ciliate and the banner back is quite hairy, both of which can only fit grandiflorus. Two other characteristics also fit only var. grandiflorus: the inflorescence length is 2-3 cm and the peduncle is 2.5-4 cm.
The single voucher from here determined as var. breweri has a dupe determined as var. grandiflorus. We left that voucher of var. breweri in the list below, but we strongly suspect var. breweri does not exist here. In addition to our measurements and the other vouchers which support the variety being grandiflorus here, Jane Strong found that some vouchers of var. breweri in the San Bernardino Mountains are recorded as growing in the quite-different habitat of open meadow near Big Bear Lake.
The Flora
For photographs of many of the plants observed on the 24 June 2015 field survey, see the Photo Gallery by Michael Charters.
The column #V gives the number of vouchers for this area.
The column #Pls gives the minimum number of plants, up to a maximum of 99, from the 24 June 2015 survey. Species found only in 2008 by Michael Charters have MC in this column. If there is uncertainty in the determination, the number has a symbol associated with it, ~ for a probable determination, ? for a more uncertain determination.
Version for printing, without lines and other text on this page: html (4 pages) or pdf Clickbook booklet (1 double-sided page). (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/) on 22 June 2015.We thank Jane Strong for comments about the number of missing species that inspired our comments in the Introduction, and for finding that Lupinus breweri var. breweri seems to grow in a different habitat than var. grandiflorus.
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