Lessingia arachnoidea
Encyclopedia
Lessingia arachnoidea is a rare species of flowering plant in the daisy family
known by the common name Crystal Springs lessingia. It is endemic to California
, where it is known from a few occurrences in the vicinity of Crystal Springs Reservoir
on the San Francisco Peninsula
. It may also exist in Sonoma County
to the north. The plant grows in chaparral
, scrub, and other local plant communities, often on serpentine soil
s. This is an annual herb producing a slender, erect stem up to 80 centimeters in maximum height. It is woolly toward the ends of the stems, less so toward the base of the plant. The leaves are narrow and sometimes toothed, the lowest approaching 11 centimeters long and the uppermost reduced in size. The inflorescence
is made up of a single flower head
at the tip of the slender stem. The flower head is lined with tiny lance-shaped phyllaries
with purplish pointed tips and sometimes a coat of woolly fibers. The head is discoid, lacking ray florets but bearing several funnel-shaped lavender disc florets with raylike lobes. The fruit is an achene
with a very hairy hard body 2 or 3 millimeters long and a small, bristly pappus
on top.
Asteraceae
The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...
known by the common name Crystal Springs lessingia. It is endemic to California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, where it is known from a few occurrences in the vicinity of Crystal Springs Reservoir
Crystal Springs Reservoir
Crystal Springs Reservoir is a pair of artificial lakes located in the northern Santa Cruz Mountains of San Mateo County, California situated in the rift valley created by the San Andreas Fault just to the west of the cities of San Mateo and Hillsborough, and I-280...
on the San Francisco Peninsula
San Francisco Peninsula
The San Francisco Peninsula is a peninsula in the San Francisco Bay Area that separates the San Francisco Bay from the Pacific Ocean. On its northern tip is the City and County of San Francisco. Its southern base is in Santa Clara County, including the cities of Palo Alto, Los Altos, and Mountain...
. It may also exist in Sonoma County
Sonoma County, California
Sonoma County, located on the northern coast of the U.S. state of California, is the largest and northernmost of the nine San Francisco Bay Area counties. Its population at the 2010 census was 483,878. Its largest city and county seat is Santa Rosa....
to the north. The plant grows in chaparral
Chaparral
Chaparral is a shrubland or heathland plant community found primarily in the U.S. state of California and in the northern portion of the Baja California peninsula, Mexico...
, scrub, and other local plant communities, often on serpentine soil
Serpentine soil
A serpentine soil is derived from ultramafic rocks, in particular serpentinite, a rock formed by the hydration and metamorphic transformation of ultramafic rock from the Earth's mantle....
s. This is an annual herb producing a slender, erect stem up to 80 centimeters in maximum height. It is woolly toward the ends of the stems, less so toward the base of the plant. The leaves are narrow and sometimes toothed, the lowest approaching 11 centimeters long and the uppermost reduced in size. The inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
is made up of a single flower head
Head (botany)
The capitulum is considered the most derived form of inflorescence. Flower heads found outside Asteraceae show lesser degrees of specialization....
at the tip of the slender stem. The flower head is lined with tiny lance-shaped phyllaries
Bract
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis, or cone scale. Bracts are often different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture...
with purplish pointed tips and sometimes a coat of woolly fibers. The head is discoid, lacking ray florets but bearing several funnel-shaped lavender disc florets with raylike lobes. The fruit is an achene
Achene
An achene is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate and indehiscent...
with a very hairy hard body 2 or 3 millimeters long and a small, bristly pappus
Pappus (flower structure)
The pappus is the modified calyx, the part of an individual disk, ray or ligule floret surrounding the base of the corolla, in flower heads of the plant family Asteraceae. The pappus may be composed of bristles , awns, scales, or may be absent. In some species, the pappus is too small to see...
on top.