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In Poly Canyon some grasslands, chaparral, coastal scrub, coastal live oak woodlands, and rock outcrop communities occur on serpentinite-derived soils. The unique demands of such soils are visible to us through changes in the vegetation occurring on them. "Serpentine barrens" is a name commonly associated with the paucity of vegetation in these areas. Serpentinitic soils support relatively fewer species, some of which are the same as those occurring on adjacent non-serpentinitic soils, others which occur only on the serpentinite. These plants tend to have numerous xeromorphic traits or characteristics that reflect the unavailability of moisture: dwarfism or nanism (smaller plant size); smaller leaf size; sclerophylls (leaves with lignified or hardened, woody surfaces); drought-deciduous leaves; and/or enlarged root systems.

Plants on serpentinitic soils may have chlorotic (pale or yellowed, malnourished) leaves. The infertility of serpentinitic soils is due to numerous factors. One factor is the absence or scarcity of one or more required elements: primary plant nutrients such as nitrogen, potassium, and phosphorus, as well as calcium. A second factor involves the unavailability of plant nutrients present. This can be caused by two things. First, the pH (typically 6.8) of these soils makes some primary plant nutrients unavailable. Second, under certain conditions, elements such as nickel, chromium, cobalt, and magnesium can inhibit the uptake of more beneficial nutrients. For example, the presence of magnesium can be antagonistic to the uptake of calcium. A third factor is the excellent drainage of these soils due to the relative absence of organic matter. This facilitates the leaching away of nutrients. A fourth factor is lower vegetative cover. As less plant litter is deposited, less organic matter becomes available in the soil to provide recycled nutrients for the plant cover, to hold moisture and nutrients in the soil, or to modify the direct exposure and also color (and, therefore, temperature and humidity) of the soil.

Four types of ecological responses by vegetation to serpentinite have been hypothesized. Endemic or obligate plants are restricted to serpentinite. Some studies suggest that serpentinite endemics actually grow equally well on non-serpentinitic soils until they are plagued by fungi or weedy vascular plants which do not survive on serpentinite. However, no evidence has been found to support the hypothesis that serpentinite endemics require certain nutritional elements found only in this substrate. Local or regional indicator plants are not restricted to serpentinite, but occur on serpentinite in areas well outside their normal ranges of distribution. Tolerant, facultative, indifferent, ubiquist, or bodenvag species are ecotypic variants of localized races of wide-ranging species which have developed a genetic tolerance to serpentinitic soils. Such plants typically exhibit somewhat different growth habits on and off the serpentinite. Non-excluded species are those plants which do not avoid serpentinite. See Table 14.

The relationship of animals to serpentinite has been addressed by some studies. Of these, several apply to species which occur in Poly Canyon.

Table 14.

Some Serpentinite Endemics
Arctostaphylos obispoensis (Ericaceae)
Calochortus obispoensis (Liliaceae)
Chorizanthe breweri (Polygonaceae)
Dudleya abramsii ssp. murina (Crassulaceae)
Some Local Serpentinite Indicators
Allium lacunosum (Liliaceae) Chorizanthe breweri (Polygonaceae)
Lomatium parvifolium (Apiaceae) Fremontodendron californica (Sterculiaceae)
Streptanthus glandulosus (Brassicaceae) Perideridia pringlei (Apiaceae)
Some Bodenvag (Indifferent) Taxa
Allium spp. (Liliaceae) Bromus spp. (Poaceae)
Carex spp. (Cyperaceae) Cercocarpus betuloides (Rosaceae)
Chlorogalum pomeridianum (Liliaceae) Eriogonum spp. (Polygonaceae)
Festuca spp. (Poaceae) Holodiscus discolor (Rosaceae)
Hordeum spp. (Poaceae) Juncus spp. (Juncaceae)
Melica spp. (Poaceae) Mimulus spp. (Scrophulariaceae)
Pentagramma triangularis (Pteridaceae) Plantago erecta (Plantaginaceae)
Poa spp. (Poaceae) Polygonum spp. (Polygonaceae)
Pteridium aquilinum (Dennstaedtiaceae) Rhamnus spp. (Rhamnaceae)
Ribes spp. (Grossulariaceae) Salix spp. (Salicaceae)
Salvia columbariae (Lamiaceae) Stipa spp. (Poaceae)
Toxicodendron diversiloba (Anacardiaceae) Zygadenus fremontii (Liliaceae)

For example, one examined the relative abundance of Botta's pocket gophers (Thomomys bottae) on adjacent serpentinitic and non-serpentinitic soils. Despite the difficulties inherent in burrowing in shallow, rocky serpentinite, pocket gophers were more numerous on these soils. Blue dicks (Dichelostemma capitatum), whose corms are a favorite food of the pocket gopher, also occur much more commonly on the serpentinitic soils. A study by Stebbins looked at speciation in plethodontid salamanders (Ensatina eschscholzia), where "certain cases of intergradation between subspecies... are related to serpentine." Shapiro studied the relationship between the serpentinite tolerant jewelflower (Streptanthus glandulosus) and larvae of the pierid butterflies Pieris sisymbrii and P. sara. "Some plants develop non-green callosities [hardened areas] at the tips of the marginal teeth [on the edges of the leaves] which mimic Pieris eggs and deter oviposition by the butterflies" presumably enabling jewelflowers to thrive in the absence of larvae that would eat them were they present.


Rock outcrops are unique among all other communities found in Poly Canyon. The dominant plants flourish under the extreme edaphic and climatic pressures that occur on bare serpentinite and/or on very thin soils. The most exposed surfaces suffer the most extreme daily fluctuations in temperature and humidity and may be inhabited by lichens. Cracks in the rocks provide microhabitats of relatively increased soil, shade, and moisture, as well as decreased exposure to insolation, temperature fluctuations, and dessication by wind. Clubmoss (Selaginella bigelovii) and goldback fern (Pentagramma triangularis) are common inhabitants of such areas. On exposed sunny, windy hillsides, leather oak (Quercus durata) and yucca (Yucca whipplei) take root in deeper soils in and around the rocks. They are accompanied by an occasional California sagebrush (Artemisia californica), buckwheat (Eriogonum spp.), Phacelia sp., or Dudleya sp. In shadier, moister areas, perhaps above a creek or seep, California maiden-hair (Adiantum jordanii) and common polypody fern (Polypodium californicum) are common.

Plants which are commonly found in serpentinite and rock outcrop communities in Poly Canyon include:
California maiden-hair (Adiantum jordanii, Pteridaceae)
*California sagebrush, coastal sagebrush (Artemisia californica, Asteraceae)
*Club-haired or Yellow Mariposa lily (Calochortus clavatus, Liliaceae)
*San Luis mariposa lily, star tulip (Calochortus obispoensis, Liliaceae)
San Luis Obispo or Mouse-leaved Dudleya (Dudleya abramsii ssp. murina, Crassulaceae)
Blochman's Dudleya (Dudleya blochmaniae ssp. blochmaniae, Crassulaceae)
Dudleya (Dudleya lanceolata, Crassulaceae)
Slender buckwheat (Eriogonum elongatum, Polygonaceae)
*California buckwheat (Eriogonum fasciculatum, Polygonaceae)
Golden yarrow (Eriophyllum confertiflorum, Asteraceae)
*Climbing bedstraw (Galium porrigens, Rubiaceae)
Small-leaved lomatium (Lomatium parvifolium, Apiaceae)
Coffee fern (Pellaea andromedifolia, Pteridaceae)
*Goldback fern (Pentagramma triangularis, Pteridaceae)
Phacelia (Phacelia imbricata, Hydrophyllaceae)
Common polypody fern (Polypodium californicum, Polypodiaceae)
*Leather oak (Quercus durata, Fagaceae)
Spike-moss, clubmoss (Selaginella bigelovii, Selaginellaceae)
Silver rock lettuce (Stephanomeria cichoriacea, Asteraceae)
*Yucca, chaparral yucca, Our Lord's candle, Quixote plant (Yucca whipplei, Liliaceae)

Descriptions of plants dominant in Poly Canyon's riparian communities follow.

California maiden-hair 1 California maiden-hair 2

California maiden-hair (Adiantum jordanii, Pteridaceae) This fern spreads by short rhizomes. Its fronds measure between 20 and 50 (possibly 70) cm. (8 and 20 (possibly 28) inches). They are twice or three times pinnately cut or lobed. Blade segments are fan-shaped. Sporangia occur along the veins and are covered by the recurved part of the blade margin. Spores are tan-colored.

Adiantum means "unwettable" in Greek. Jordanii may refer to Alexis Jordan, a 19th century French botanist.

*California sagebrush, coastal sagebrush
(Artemisia californica, Asteraceae)
click here for description

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*Club-haired or Yellow Mariposa lily (Calochortus clavatus, Liliaceae) This showy wildflower grows 50 to 100 cm. (20 to 40 inches) tall from bulbs. Its 10- to 20-cm. (4- to 8-inch) leaves are basal and wither before the plant blooms. One to six erect flowers are arranged in an umbel-like inflorescence. The three petals are deep, vivid yellow against which background the six purple anthers are prominent. The petals measure approximately 5 cm. (2 inches) long, each bearing a round nectary. They form a cup within which there is a conspicuous ring of club-shaped hairs over the nectaries. Blooms appear from April through June. The fruits are 3-angled septicidal capsules. This Mariposa lily is uncommon, but can be seen in Poly Canyon, particularly in grassy serpentinite communities.

Calochortus is Greek and means "beautiful grass." Clavatus refers to the club-shaped hairs on the inner surface of the petals.

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*San Luis Mariposa lily, star tulip (Calochortus obispoensis, Liliaceae) The San Luis Mariposa lily is a splendid wildflower that grows 30 to 60 cm. (1 to 2 feet) tall from a bulb. Its 20- to 30-cm. (8- to 12-inch) basal leaves wither before the plant blooms. The inflorescence is erect and contains two to six flowers. The three ovate petals measure about 10 to 20 mm. (1/2 to 1 inch) long. They are deep yellow to orange and coarsely hairy inside, fringed, and bear a dark tuft of hairs at the tip. Each petal has a round nectary which is nearly hidden by dense hairs. Blooming usually occurs around late May or early June. These lilies grow on rocky, grassy slopes in serpentinite and chaparral communities. They are rare.

The bulbs of the star tulip were eaten.

Calochortus is Greek and means "beautiful grass." Obispoensis refers to San Luis Obispo, California, the only county where this species occurs. The San Luis Mariposa lily is the logo for the local chapter of the California Native Plant Society.

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San Luis Obispo or Mouse-leaved Dudleya (Dudleya abramsii ssp. murina, Crassulaceae) This perennial has a simple caudex above the soil surface. The evergreen leaves are somewhat glaucous, oblong-lanceolate, and 3- to 11-cm. (11/4-to 41/3-inch) long. There are fewer than 30 leaves per rosette, and fewer than ten rosettes per plant. The 5-merous flower has pale yellow 8- to 13-mm. (1/3-to 1/2-inch) petals flecked with purple, with a purple keel. The fruit is a cluster of five erect follicles. The plant exudes a purple dye when crushed. San Luis Obispo Dudleya is uncommon. It grows on serpentinite outcrops.

W.R. Dudley, 1849-1911, was a botanist in the western United States. Leroy Abrams was a botanist at Stanford University. Murina means "mouse gray" or "like a mouse."


Dudleya (Dudleya lanceolata, Crassulaceae) This perennial has an erect caudex. The rosette of 5- to 30-cm. (2- to 12-inch) fleshy, oblong-lanceolate, evergreen leaves. These may or may not be glaucous. The inflorescence is a one-sided cyme. Flowers have five bright yellow to red petals. Blooms appear May through July. The fruit is a cluster of five erect follicles. Dudleya is found on rocky slopes.

W.R. Dudley, 1849-1911, was a botanist in the western United States. Lanceolata refers to the shape of the leaves.

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Slender buckwheat (Eriogonum elongatum, Polygonaceae) This is a 6- to 18-dm. (2- to 6-foot) perennial. Leaves are mostly basal, with some cauline. The 10- to 30-mm. (1/2- to 11/2-inch) leaf blades are elliptic, wavy-margined, and tomentose. The inflorescence is cyme-like and open with long, wand-like branches. The white flowers are borne in small sessile clusters along the branches. They measure about 1/4 cm. (1/10-inch) across and bloom from August through November. The fruit is a 2- to 3-mm. (1/8-inch), three-angled achene.

Eriogonum is Greek for "woolly knees," referring to the hairy nodes of some species. Elongatum means "elongate."

*California buckwheat
(Eriogonum fasciculatum, Polygonaceae)
click here for description

Golden yarrow
(Eriophyllum confertiflorum, Asteraceae)
click here for description

*Climbing bedstraw
(Galium porrigens, Rubiaceae)
click here for description

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Small-leaved lomatium (Lomatium parvifolium, Apiaceae) This 11/2- to 4-dm. (6- to 16-inch) perennial develops from a slender taproot. It has short stems. Its three times pinnate leaves have spiny toothed leaflets. The inflorescence is a compound umbel containing flowers with yellow petals. Fruits are 8- to 14-mm. (1/3- to 2/3-inch) elliptic flattened mericarps. In Poly Canyon, small-leafed lomatium is usually found growing in serpentinitic soils.

Lomatium is Greek for "bordered," referring to the prominent marginal wing on the fruits. Parvifolium means "small-leaved."

Coffee fern 1 Coffee fern 2

Coffee fern (Pellaea andromedifolia, Pteridaceae) This fern spreads by long, branched rhizomes. The 20- to 60-cm. (8- to 24-inch) leaves are bluish green to purplish gray. The blades are generally three (possibly two or four) times pinnately divided into many small leaflets. Sporangia are found in bands near the curled-under margins of the leaflets. Spores are tan to light yellow.

Pellaea is Greek for "dusky," referring to the bluish-gray leaves. Andromedifolia means "leaves like those of the genus Andromeda, Ericaceae.

*Goldback fern
(Pentagramma triangularis, Pteridaceae)
click here for description


Phacelia (Phacelia imbricata, Hydrophyllaceae) This perennial has 20- to 120-cm. (8- to 48-inch) stiff-hairy stems. The 50- to 150-mm. (2- to 6- inches) leaves are mostly basal. They are narrowly lanceolate to ovate and are dissected into three to 15 segments. The inflorescence is a cluster of dense, coiled, one-sided cymes. The flowers have a 4- to 7-mm. (1/6- to 1/4-inch) corolla that is cylindric to bell-shaped and white to lavender. The fruit is a stiff-hairy, ovoid, and inconspicuous capsule.

Phacelia is Greek for "cluster," referring to the dense inflorescence. Imbricata means "overlapping," in reference to the overlapping calyx lobes.

polypody fern

Common polypody fern (Polypodium californicum, Polypodiaceae) This is a perennial fern spreading by rhizomes. Its leaves are summer-deciduous. The 10- to 25-cm. (4- to 10-inch) blades are deltate to ovate and are pinnately compound. The leaflet blade margins are minutely serrate. Sporangia are grouped in round sori on the underside of the leaflets. The sori appear somewhat sunken and have no indusium (covering).

Polypodium is Latin and means "many-footed," referring to the rhizomes. Californicum means "of California."

Leather oak
(Quercus durata, Fagaceae)
click here for description


Spike-moss, clubmoss (Selaginella bigelovii, Selaginellaceae) This is a 5- to 15-cm. (2- to 6-inch) tall mat-forming plant with ascending to erect, clumping stems. Its tiny leaves are 6-ranked, overlapping, appressed, and scale-like, linear in shape, and bristle-tipped. The margins have somewhat rigid hairs. This is a non-flowering plant tha produces spores in small, terminal cone-like strobili. The sporangia are borne in the axils of 4-ranked sporophylls (scale leaves). Terminal cones are generally smaller than 1 cm. (1/2 inch). These are lanceolate to ovate in shape. There are two kinds of spores: orange megaspores and much smaller yellow microspores. During dry seasons, this plant may appear to be dead, only to resume growth as moisture and cooler temperatures return. Because of this, it is sometimes called the resurrection plant.

Selaginella is a diminutive form of the Latin word selago which is the ancient name for some Lycopodium. Bigelovii refers to Professor Bigelow of Boston.

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Silver rock lettuce (Stephanomeria cichoriacea, Asteraceae) This 5- to 15-dm. (20- to 60-inch) perennial has a large root crown. Its stems are tomentose. 5- to 18-cm. (2- to 7-inch) oblong to lanceolate leaves grow in a basal rosette. The leaves have mostly smooth edges (possibly with a few teeth). The inflorescence is a pink-flowered, dandelion-like head of ten to 15 florets. It blooms in summer. The fruit is a five-angled, smooth, brownish achene.

Stephanomeria comes from Greek and means "wreath division." Cichoriacea comes from cichoreum meaning "endive."

*Yucca, chaparral yucca, Our Lord's candle, Quixote plant
(Yucca whipplei, Liliaceae)
click here for description