Flora of Margarita Peak Area

Introduction
Physical Setting and Geology
The Flora

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Introduction

Margarita Peak is the highest point in the Santa Margarita Mountains at an elevation of 3189 feet. It is in San Diego County north of Camp Pendleton, south of the San Mateo Canyon Wilderness Area and west of De Luz (see location map).

Although many people think Margarita Peak is part of the Cleveland National Forest, it is part of a privately-owned 1,206 acre parcel south of the Forest. In August 2007, this parcel was purchased by the Trust for Public Land for $3.1 million obtained from the state and federal governments. Nearly $1.6 million came from the California Wildlife Conservation Board. The rest came from Navy funds provided by Congress to purchase lands to form a buffer zone of "no development" next to military bases, in this case Camp Pendleton.

The parcel was turned over to the Fallbrook Land Conservancy to own and manage, with the Navy holding an easement on the land that precludes development. Unfortunately, no funds for stewardship of the parcel came along with the transfer, so the Fallbrook Land Conservancy must raise funds to manage the parcel. If you would like to help, contact them.

It is also easy to confuse Margarita Peak with Margarita Lookout, which is a peak ~0.9 miles to the north / northwest along the main ridge of the Santa Margarita Mountains, within the National Forest.

Margarita Peak is currently closed to the public until the Fallbrook Land Conservancy installs barriers to keep out off-road vehicles and surveys the land for plants and animals. The land will then be opened to the public for hiking, bird watching and other forms of "passive" recreation.

This page gives the flora of the Margarita Peak parcel from the first such survey.

Physical Setting and Geology

This parcel is at the southernmost end of the Santa Ana Mountains, where the mountains are largely terminated by the Santa Margarita River. The coastal plain is to the south. The parcel consists of two north-south ridges on the west and east, with the region in-between heavily dissected by Roblar Creek, a tributary to the Santa Margarita River. (Roblar is oak grove in Spanish.) The two ridges each have a nearly-constant elevation along the ridgeline, with variations of only ~100 feet between peaks, and an overall change in elevation to the south of only ~100 feet. The flatness of these ridges is due to them being remnants of the old fairly-flat landscape before the land was uplifted ~2 million years ago and began to be dissected.

The following map shows the extent, topography and geology of this parcel:

See also Google satellite view of entire parcel and neighboring area.

The parcel is delineated by the blue arrows; the thick light red bands also line the parcel on three sides. The black line along the top is a mostly east-west firebreak and a short trail to Margarita Peak, surveyed on 11/21/07; the green line along the top and right side is the continuation of that firebreak surveyed on 6/13/08. The two yellow lines and one blue line delineate labeled geologic provinces. An elevation profile along the horizontal red arrow near the top is given below.

The parcel is bordered on the north by the Cleveland National Forest, on the west and south by Camp Pendleton, and on the east by private property. The parcel spans 1.95 miles along its northern end, 1.43 miles along its southern end, and averages 1.1 miles in north-south extent except along the extreme westernmost portion.

The highest elevation is 3189 feet at Margarita Peak in the northwest corner. The lowest elevation is ~1480 feet in Roblar Creek on the southernmost edge of the property near its middle, giving a range in elevation of ~1710 feet.

Except for a very small portion north of the fire break shown as the black line at the top of the above map, the entire property burned in 2003. The last previous burn was in (1960?). See Google satellite view showing unburned area.

The large-scale geology of the parcel is delineated by the two yellow contours and one blue contour. The yellow contours are from the 2005 Geologic Map of the Oceanside 30 x 60-minute Quadrangle (see Geologic Map (4.1 MB) and Correlation and description of map units). The dark blue contour is from the 1966 Santa Ana Sheet of the Geologic Map of California.

However, we note that the geology shown on the above map is from aerial photography and/or large-scale surveys. There is considerable disagreement among the three recent geologic maps of this area (see the previous two geologic maps). The interpretation here seems to be the one that matches what we observed on 21 November 2007 and on satellite images.

The description of the units from the 2005 map are:

• Mzu. Metasedimentary and metavolcanic rocks undivided (Mesozoic) - Wide variety of low- to high-metamorphic grade metavolcanic and metasedimentary rocks that are mostly volcaniclastic breccia and metaandesitic flows, tuffs and tuff-breccia.

• Khg. Heterogeneous granitic rocks (Cretaceous) - A wide variety of heterogeneous granitic rocks occur in Oceanside quadrangle. Some heterogeneous assemblages include large proportions of metamorphic rocks.

• Kgdfg. Quartz-bearing diorite undivided (mid-Cretaceous) - Mostly massive, medium-grained, dark-gray biotite-hornblende quartz-bearing diorite.

In much previous literature, similar rocks have been identified as follows:

• The metasedimentary rocks have been called the Bedford Canyon Formation, the former sea floor sediments from ~100 - ~200 million years ago that were metamorphosed by plutonic activity ~100 million years ago. This formation is easily weathered and generally is not exposed on the surface except where there has been recent erosion.

• The metavolcanic rocks have been called the Santiago Peak Metavolcanics, and are typically found in a narrow band along the west edge of southern Riverside and San Diego Counties. These were basaltic lavas erupted from volcanoes of ~100 million years ago, deposited on portions of the Bedford Canyon Formation. This formation is also easily weathered and generally is not exposed on the surface.

• The quartz-bearing diorite, and the granitic rocks, have been called the Woodson Mountain Granodiorite, the Bonsall Tonalite, and the San Marcos gabbro. The rocks formed in the cooled magma chambers of ~100 million years ago. Some of these rocks are fairly resistant to erosion, and often are exposed at the surface.

In the following, we use Bedford, Santiago, quartz-bearing diorite, and granitic simply as easy to understand labels for these rock types.

These geologic units are readily apparent in the topography of this parcel. The following plot is the elevation cross-section at the location of the horizontal red arrow in the previous plot:

There is a distinct change in slope where the rock types change, and the terrain is quite different in each of the units. The quartz-bearing diorite supports the steeper slopes of the higher elevation ridge in the west. Note the change in slope on the east side of this ridge when the rocks change to the mix of granitic and metasedimentary (granitic / Bedford) rocks.

Since the metasedimentary and metavolcanic rocks (Bedford / Santiago) are easily eroded, they cannot support steep slopes except where they are very recently eroded. Thus it is no surprise that the Roblar Creek drainage developed in these rocks, and the valley has a very shallow slope on its sides.

A slope change is again apparent in the east when the rocks change to metasedimentary (Bedford) rocks. The ridge on the east is significantly lower than the ridge on the west, with gentler slopes, due to the weakness of these rocks.

On our survey on 19 November 2007, we found that the soil on the west slope of the Margarita Peak ridgeline is red, whereas the soils are brown on the east slope. This is a bit puzzling since the underlying rocks are the same on both the east and west slope of that ridgeline, as shown in the geologic map and by our casual field observations.

It is expected that the underlying rocks will influence at least some of the species distributions.

See also Pictures of this area and some of these rocks.

The Flora

The property is mapped in Beauchamp (1986) as about 1/3 chamise chaparral, mostly in the Roblar Creek canyon and to its northeast, with the rest mixed chaparral, except for a small amount of southern oak woodland along its northwest edge.

Survey Details

The plant list given below was obtained from two surveys. The first survey was of 1.4 miles on a firebreak along the northwestern edge of the property on 21 November 2007 by the four authors. The survey was done along the black line extending mostly east-west at the top of the above map, and included the sections of the black line slightly north of the property boundary.

The survey sampled many of the environments in the northern part of the property with the notable exclusion of the easternmost ridge. The survey included the Roblar Creek area, the Roblar Creek Valley, the east- and west-facing slopes of the westernmost ridge, and Margarita Peak itself. The survey included all three geologic units in the 2005 geologic map.

Unfortunately, this was possibly the worst time to do a botanical survey in the last 100 years, near the end of a record drought year and near the end of a record drought decade, after a fire had burned most of the property in 2003. Hence this survey is very incomplete for annuals and perennials, and possibly even for shrubs that have not yet returned after the fire.

Many identifications were done from dead plant remnants from as much as two years ago, and few live plants were in bloom. Identifications that we estimated were less than 95% confidence are given with a question mark; ones felt to be 95% confidence are given with a "~"; the others were felt to have almost 100% confidence. However, given the poor condition (for identification) of these plants when surveyed, it is possible that even a few of almost 100% confidence determinations may prove erroneous.

The second survey was done on 13 June 2008, near the end of the blooming season for most species after a decent rainfall year, by Tom Chester and Mike Peters. This survey did not resurvey most of the area of the first survey. Instead, this survey explored 2.4 miles of a cross-section of Roblar Valley and the ridgeline area on the east of this parcel. The route is shown in green on the above map.

The second survey sampled an west-facing slope of the easternmost ridge, the fairly extensive top of that ridge, and a bit of the east-facing slope.

This survey resolved all of the uncertain plant determinations from the first survey, except for four species found only on the first survey. It added a few species also with some uncertainty on their determinations since those species were lacking some elements needed for their confident determination.

Survey Results

The first survey yielded 82 taxa, 68 native and 14 non-native, in the 1.4 miles of surveyed fire break. The second survey yielded 94 taxa, of which 68 taxa were found in the first survey, and 26 were new taxa for the checklist.

The total number of taxa in the checklist below is 108, of which 104 are fairly confidently-identified. Of those 104 taxa, 89 are native and 15 are non-native.

Six of these taxa are in the CNPS Inventory of Rare and Endangered Plants:

CNPS List	Latin Name	Common Name
List 1B.1	Arctostaphylos rainbowensis	Rainbow manzanita
List 1B.3	Horkelia truncata	Ramona horkelia
List 4.2	Holocarpha virgata ssp. elongata	graceful tarplant
List 4.3	Pickeringia montana var. tomentosa	chaparral pea
List 4.3	Polygala cornuta var. fishiae	Fish's milkwort
List 4.3	Swertia parryi	Parry's green-gentian

The location and abundance of these taxa are as follows:

• Arctostaphylos rainbowensis. We found about 20 mature specimens that showed no evidence of hybridization with the much more abundant A. glandulosa. These specimens all had globose burls, glabrous stems and twigs, and scale-like inflorescence bracts ~2 mm in length throughout. One specimen had fruit, which was purplish.

  We examined numerous specimens of A. glandulosa ssp. zacaensis; none showed any evidence of hybridization with A. rainbowensis. All examined specimens had hairy or glandular-hairy twigs, and lower inflorescence bracts that were leaf-like, 5-10 mm in length. All fruit were a light red color, without any purplish color. Burls tended to be flat-topped, but many specimens were young and their burls were indistinguishable from a globose burl.

  Thus these two species appear to not interbreed here.

• Horkelia truncata. This property has one of the largest collections that we have seen. This species is numerous on the disturbed area below the fireroad, from Roblar Creek west to the beginning of the eastern slope at the base of Margarita Peak. This species was only found in the Bedford / Santiago geologic unit, but it may just prefer the flattish slopes found in that unit.

• Holocarpha virgata ssp. elongata. We found ~50 plants of this annual, on the slopes above Roblar Creek and on the western slopes below Margarita Peak.

• Pickeringia montana var. tomentosa. The eastern ridgeline has at least 30 plants of this species, concentrated to one location.

• Polygala cornuta var. fishiae. We found three plants in the short section of Roblar Creek we surveyed, and expect it lines at least portions of the Creek.

• Swertia parryi. This species is found in the Roblar Creek drainage near the bottom, a minimum of 20 plants.

The rarest taxa here, defined as the species found least often in our database of 128 plant trail guides and 85 digitized floras, a total of 213 lists, are in the following table:

# lists	Taxon
8	Pickeringia montana var. tomentosa
9	Horkelia truncata
11	Calamagrostis koelerioides
12	Arctostaphylos rainbowensis
15	Rhamnus tomentella ssp. tomentella
15	Styrax officinalis var. redivivus
16	Calystegia macrostegia ssp. arida
17	Vulpia myuros
18	Cheilanthes clevelandii
19	Polygala cornuta var. fishiae

For comparison, the taxon on this trail found in the most lists is golden yarrow, Eriophyllum confertiflorum var. confertiflorum, found on 118 lists.

Bush poppy, Dendromecon rigida, is abundant almost throughout the area surveyed, as expected four years after a burn. However, we saw no young plants that are usually found four years after a fire of the other species present here, such as Ceanothus tomentosus, C. crassifolius, S. mellifera, and Eriogonum fasciculatum. Seedlings of these species may have germinated, but succumbed to the severe drought of the last two years.

The area around Margarita Peak escaped the 2003 fire, and has what appears to be a climax community composed almost entirely of just three species: chamise, hoaryleaf ceanothus and Arctostaphylos glandulosa. The area along the eastern ridgeline has very similar portions.

Black sage, Salvia mellifera, and Cleveland sage, S. clevelandii, have an interesting distribution here. Black sage is much less abundant than Cleveland sage, and is found only on west and east ends of our survey, and thus is only on the west-facing slopes. Cleveland sage is found throughout, but drops out in some of the areas that have black sage.

The list of shrubs that we did not find is possibly as interesting as the species we found:

Arctostaphylos glauca
Artemisia californica
Baccharis emoryi 
Baccharis pilularis
Dudleya lanceolata
Malacothamnus sp.
Opuntia vaseyi
Rhamnus crocea 
Rhus integrifolia
Xylococcus bicolor

All of the species on the above list are found in nearby areas, and many of those species are abundant nearby. Each of these species would have easily been observed in our survey if they were present here.

In addition, we saw no Chamaesyce, Cryptantha, or Phacelia species. This was quite surprising, since similar areas at the Santa Rosa Plateau Ecological Reserve would have extensive populations of Cryptantha, and a much larger number of annual species lining the trail.

The only reason that comes to mind for the paucity of annual species along the trail is that this area is in the middle of quite pristine chaparral, which may largely exclude such species.

Species Notes

Rhamnus tomentella, R. californica. We found that the underneath of the leaves on about 90% of the coffeeberry plants here were very hairy and very soft to the touch, which would key to Rhamnus tomentella. However, about 10% of the plants had totally glabrous leaves, and would key to R. californica. We strongly suspect there is only one species here, since we have found similar variation in these coffeeberries wherever we have surveyed, and have simply arbitrarily called them R. tomentella here.

See, for example, notes on the SnJt Devils Slide Trail population.

Calystegia macrostegia. The plants seen on 6/13/08 had the narrow leaves of ssp. tenuifolia, but it is now fairly clear that there is no actual difference between subspecies arida, intermedia, and tenuifolia. We have simply called these plants ssp. arida, just in case the C. macrostegia subspecies other than these three are actually valid.

See Calystegia macrostegia subspecies intermedia and tenuifolia are bogus.

The Plant List

The estimate of abundance for each taxa is given as the number of total plants seen and the number of locations for each species. These numbers are intended to refer to the entire area, so there is no difference between "on-trail" and "off-trail" as applies to our plant trail guides elsewhere.

The main intended use of this abundance estimate is to note which species are uncommon in this parcel. We do not attempt to quantify the relative abundance of common plants. Thus the maximum number of plants given is 99, and the maximum number of locations is 9.

We define a single location to include all areas within a radius of ~0.1 mile. This is much larger than the radius of ~0.01 mile used in our plant trail guide). For example, the Ramona horkelia was found over a stretch of ~0.3 miles, so is reported as being in 3 locations.

Species found only in the Roblar Creek drainage are noted in the column labeled RC. (Roblar is oak grove in Spanish.)

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)

#	Latin Name	(*)Common Name	# Plants	# Locations	RC
Ferns and Fern Allies
Pteridaceae		Fern Family
1	Cheilanthes clevelandii	scaly lipfern	1	1
2	Pellaea mucronata var. mucronata	bird's-foot fern	10	2
3		unk fern	1	1
Dicots
Anacardiaceae		Sumac Family
4	Malosma laurina	laurel sumac	10	5
5	Rhus ovata	sugar bush	40	9
6	Rhus trilobata	basketbush	1	1	RC
7	Toxicodendron diversilobum	poison oak	10	2	RC
Apiaceae		Carrot Family
8	Foeniculum vulgare	*fennel	10	2
9	Lomatium dasycarpum ssp. dasycarpum	woolly-fruited lomatium	20	2
10	Lomatium lucidum	shiny lomatium	10	5
Asteraceae		Sunflower Family
11	Agoseris grandiflora	grand mountain dandelion	20	2
12	Ambrosia psilostachya	western ragweed	10	1	RC
13	Artemisia douglasiana	mugwort	10	1	RC
14	Baccharis salicifolia	mule fat	5	1	RC
15	Centaurea melitensis	*tocalote	99	9
16	Chaenactis artemisiifolia	meally white pincushion	10	2
17	Erigeron foliosus var. foliosus	leafy daisy	10	9
18	Eriophyllum confertiflorum var. confertiflorum	golden yarrow	99	9
19	Filago gallica	*narrowleaf filago	99	9
20	Gnaphalium californicum	California everlasting	10	5
21	Gnaphalium canescens ssp. beneolens	fragrant everlasting	20	9
22	Gnaphalium canescens ssp. microcephalum	white everlasting	3	2
23	Hazardia squarrosa var. grindelioides	saw-toothed goldenbush	30	9
24	Helianthus gracilentus	slender sunflower	99	9
25	Heterotheca grandiflora	telegraph weed	20	1
26	Holocarpha virgata ssp. elongata	graceful tarplant	50	9
27	Hypochaeris glabra	*smooth cat's ear	50	9
28	Lessingia filaginifolia var. filaginifolia	California-aster	5	1
29	Madia gracilis	slender madia	10	1
30	Sonchus oleraceus	*sow thistle	3	2
31	Stephanomeria diegensis	San Diego wreathplant	30	9
32	Venegasia carpesioides	canyon sunflower	20	9
33		*thistle	1	1
Brassicaceae		Mustard Family
34	Hirschfeldia incana	*shortpod mustard	10	1	RC
Caprifoliaceae		Honeysuckle Family
35	Lonicera subspicata var. denudata	southern honeysuckle	10	5
36	Sambucus mexicana	blue elderberry	2	2
Caryophyllaceae		Pink Family
37	Silene laciniata ssp. major	southern Indian pink	20	4
Cistaceae		Rock-Rose Family
38	Helianthemum scoparium	rush-rose	99	9
Convolvulaceae		Morning Glory Family
39	Calystegia macrostegia ssp. arida	southern California morning-glory	10	9
Cucurbitaceae		Gourd Family
40	Marah macrocarpus var. macrocarpus	wild-cucumber	2	2
Cuscutaceae		Dodder Family
41	~Cuscuta californica	~California dodder	10	2
Ericaceae		Heath Family
42	Arctostaphylos glandulosa ssp. zacaensis	Eastwood manzanita	99	9
43	Arctostaphylos rainbowensis	Rainbow manzanita	20	9
Euphorbiaceae		Spurge Family
44	Eremocarpus setigerus	dove weed	10	1
Fabaceae		Pea Family
45	Lathyrus vestitus var. alefeldii	San Diego pea	1	1
46	Lotus scoparius var. scoparius	deerweed	99	9
47	Pickeringia montana var. tomentosa	chaparral pea	30	5
Fagaceae		Oak Family
48	Quercus acutidens	Torrey's scrub oak	50	9
49	Quercus agrifolia var. agrifolia	coast live oak	40	9
50	Quercus wislizeni var. frutescens	interior live oak	1	1
Gentianaceae		Gentian Family
51	Centaurium venustum	canchalagua	30	9
52	Swertia parryi	Parry's green-gentian	20	2
Geraniaceae		Geranium Family
53	Erodium brachycarpum	*short-fruited filaree	1	1
Grossulariaceae		Gooseberry Family
54	Ribes indecorum	white-flowering currant	10	3
Hydrophyllaceae		Phacelia Family
55	Eriodictyon crassifolium var. crassifolium	thick-leaved yerba santa	20	5
Lamiaceae		Mint Family
56	Salvia apiana	white sage	1	1
57	Salvia clevelandii	Cleveland sage	99	9
58	Salvia mellifera	black sage	20	3
Papaveraceae		Poppy Family
59	Dendromecon rigida	bush poppy	99	9
Plantaginaceae		Plantain Family
60	Plantago lanceolata	*English plantain	30	2	RC
Polemoniaceae		Phlox Family
61	Navarretia hamata ssp. hamata	hooked skunkweed	99	9
Polygalaceae		Milkwort Family
62	Polygala cornuta var. fishiae	Fish's milkwort	3	1	RC
Polygonaceae		Buckwheat Family
63	Chorizanthe staticoides	Turkish rugging	10	1
64	Eriogonum fasciculatum var. foliolosum	California buckwheat	50	9
Primulaceae		Primrose Family
65	Anagallis arvensis	*scarlet pimpernel	30	9
Ranunculaceae		Buttercup Family
66	Clematis lasiantha	virgin's bower	30	9
Rhamnaceae		Buckthorn Family
67	Ceanothus crassifolius	hoaryleaf ceanothus	30	9
68	Ceanothus leucodermis	chaparral whitethorn	20	9
69	Ceanothus tomentosus var. olivaceus	Ramona-lilac	20	9
70	Rhamnus ilicifolia	hollyleaf redberry	5	5
71	Rhamnus tomentella ssp. tomentella	hoary coffeeberry	10	9
Rosaceae		Rose Family
72	Adenostoma fasciculatum	chamise	99	9
73	Cercocarpus minutiflorus	San Diego mountain mahogany	20	1	RC
74	Heteromeles arbutifolia	toyon	50	9
75	Horkelia truncata	Ramona horkelia	50	6
76	Prunus ilicifolia ssp. ilicifolia	hollyleaf cherry	5	5
Rubiaceae		Bedstraw Family
77	Galium angustifolium ssp. angustifolium	narrowleaf bedstraw	40	9
78	Galium nuttallii ssp. nuttallii	climbing bedstraw	1	1
Scrophulariaceae		Snapdragon Family
79	Antirrhinum nuttallianum ssp. nuttallianum	purple snapdragon	5	2
80	Cordylanthus rigidus ssp. setigerus	bristly bird's beak	99	9
81	Keckiella cordifolia	heartleaf penstemon	10	3
82	Mimulus aurantiacus	bush monkeyflower	20	5
83	Scrophularia californica ssp. floribunda	California bee plant	3	1
Solanaceae		Nightshade Family
84	Solanum parishii	Parish's purple nightshade	5	5
Styracaceae		Storax Family
85	Styrax officinalis var. redivivus	California snowdrop bush	40	9
Verbenaceae		Vervain Family
86	Verbena lasiostachys var. lasiostachys	western vervain	10	1	RC
Monocots
Cyperaceae		Sedge Family
87	~Carex triquetra	~triangular-fruit sedge	1	1
Juncaceae		Rush Family
88	Juncus macrophyllus?	long-leaved rush?	2	1	RC
Liliaceae		Lily Family
89	Calochortus splendens	splendid mariposa lily	10	2
90	Calochortus weedii var. weedii	yellow mariposa lily	50	9
91	Chlorogalum parviflorum	small-flowered soap plant	10	3
92	Chlorogalum pomeridianum var. pomeridianum	soap plant	10	3
93	Dichelostemma capitatum ssp. capitatum	blue dicks	10	1
94	Yucca whipplei	chaparral yucca	50	9
95	Zigadenus fremontii	white star-lily	4	3
Poaceae		Grass Family
96	Achnatherum coronatum	giant needlegrass	30	9
97	Agrostis pallens	seashore bentgrass	20	9
98	Avena barbata	*slender wild oats	30	9
99	Bromus diandrus	*ripgut brome	5	1	RC
100	Bromus hordeaceus	*soft chess	10	1	RC
101	Bromus madritensis ssp. rubens	*red brome	99	9
102	Calamagrostis koelerioides	fire reedgrass	20	9
103	Cortaderia sp.	*pampas grass	1	1
104	Elymus glaucus ssp. glaucus	blue wildrye	3	1	RC
105	Gastridium ventricosum	*nit grass	50	9
106	Melica imperfecta	coast-range melic	10	5
107	Nassella lepida	foothill needlegrass	50	9
108	Vulpia myuros	*rattail fescue	50	9

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