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U.S. Fish and Wildlife Service
Yreka Fish and Wildlife Office
1829 S. Oregon Street
Yreka, California 96097
Siskiyou Mariposa Lily
The Siskiyou Mariposa Lily (Calochortus persistens)
is a Federal
Candidate species. Candidate species are those for which the
Service has on file sufficient information on biological vulnerablility
and threats to support proposals to list them as endangered or threatened.
This small lily is known from two populations and consists only
of a few thousand plants on Federal and private land in northern California
and southern Oregon. The plant stands four to six inches high, with
a short, unbranched stem. A single grey-green, strap-shaped leaf
appears to emerge directly from the ground. Similar to a tulip,
the Siskiyou Mariposa Lily produces one to three pink to lavender, three-petaled,
cup shaped flowers; the inner and lower portion of the petals are yellowish
and covered with gold hairs.
© 1983 Steve Lowens
© 1982 Steve Lowens
The Siskiyou Mariposa
Lily is one of many endemic species found in the Klamath
Siskiyou mountain region. Suitable habitat for this perennial
herb is found in open-shrub communities, in shallow metamorphic soils
on exposed ridgetops, rocky outcrops, and talus slopes. One of the
two populations is found along a ridge which has one of the highest rates
of lightning strikes in the area, suggesting that fire may be an important
factor for this species. This species shows characteristics of being
long-lived with a slow growth rate and low rate of reproduction.
Threats to this species include its restricted range, predation of leaves,
buds, flowers, and fruits by deer and insects, competition from exotic
invasive species (especially Dyer’s woad or Marlahan mustard), lack
of adequate regulatory mechanisms, mechanical disturbance, and changes
to natural fire regimes. C. persistens is considered a rare species
in California and is designated as a Sensitive Species by the U. S. Forest
Slender Orcutt Grass
The slender Orcutt grass (Orcuttia tenuis) is one of eight other
pool-associated plants listed under the ESA (Federal Register Vol. 62, No. 58). Vernal pools in California are generally
small, seasonally aquatic ecosystems that are inundated in the winter and
dry slowly in the spring and summer, creating unusual ecological conditions
supporting unique biota. Once wide-spread in California, vernal pools
have been significantly reduced due to urbanization and agriculture over
the last two hundred years; therefore, most species associated with these
habitats are considered at risk. O. tenuis is an annual grass that
grows about two to six inches in height, and is described as being “weakly-tufted
© 1991 Dean Wm. Taylor
© 2000 Robert E. Preston, Ph.D.
In northern California, vernal pools are often found on remnant alluvial
fans, high stream terraces and recent basalt flows. Disjunct populations
of O. tenuis occur in these pools in Tehama, Lake, Lassen, Plumas,
Sacramento, Shasta, and Siskiyou counties. Two known populations
occur on Federal and private land in southern Siskiyou County.
Critical habitat for slender Orcutt grass was originally designated in a final rule published in 68 FR 46683 on August 6, 2003. Economic exclusions from the 2003 final rule were evaluated in 70 FR 46923; published on August 11, 2005. Administrative revisions with species-by-unit designations were published in 71 FR 7117 on February 10, 2006, providing six critical habitat units (with 19 subunits) totaling 38,127 hectares (94,213 acres).