Calochortus tiburonensis
Encyclopedia
Calochortus tiburonensis (the Tiburon Mariposa Lily) is a rare member of the genus Calochortus
in the family Liliaceae
. It is endemic to Marin County, California
, where it is known only from one population on Ring Mountain
. There it occurs on a single serpentine
outcrop in grasslands from 0-200 meters elevation.
growing from a bulb
to 10-60 cm in height with a single leaf. It produces anywhere from 2 to 7 erect flowers annually on a branching stem. The ciliate, light yellow-green petal
s are streaked with purplish-brown. When mature, ovaries form capsule
full of small, dark brown seeds.
, to its proximity to a dense population center, and to its confinement to a single population of plants. The population grows on land owned by the Marin County Open Space District, an area previously owned and preserved by The Nature Conservancy
. It was first brought to the attention of science in 1971, and was described to science in 1973. It is protected along with a number of other rare serpentine soil
s endemics that grow on and around Ring Mountain.
The plant has probably always been rare and limited to its current distribution on the Ring Mountain outcrop. A 1991 estimate placed the total population size at about 40,000 individuals. While the land is protected, the flora upon it are still vulnerable to events such as wildfire
s or drought
, and to damage from hikers
, cyclists
, vandals
, and wildflower collectors.
Calochortus
Calochortus is a genus of bulbous plants that includes 70 species from British Columbia to Guatemala and east to Nebraska. Calochortus is the most widely dispersed genus of Liliaceae on the North American Pacific coast. Of these, 28 species are endemic to California...
in the family Liliaceae
Liliaceae
The Liliaceae, or the lily family, is a family of monocotyledons in the order Liliales. Plants in this family have linear leaves, mostly with parallel veins but with several having net venation , and flower arranged in threes. Several have bulbs, while others have rhizomes...
. It is endemic to Marin County, California
Marin County, California
Marin County is a county located in the North San Francisco Bay Area of the U.S. state of California, across the Golden Gate Bridge from San Francisco. As of 2010, the population was 252,409. The county seat is San Rafael and the largest employer is the county government. Marin County is well...
, where it is known only from one population on Ring Mountain
Ring Mountain (California)
Ring Mountain is an elevated landform on the Tiburon Peninsula in Marin County, California. This mountain was named for George E. Ring, who served as a Marin County Supervisor from 1895 to 1903.A number of rare and endangered flora inhabit Ring Mountain...
. There it occurs on a single serpentine
Serpentinite
Serpentinite is a rock composed of one or more serpentine group minerals. Minerals in this group are formed by serpentinization, a hydration and metamorphic transformation of ultramafic rock from the Earth's mantle...
outcrop in grasslands from 0-200 meters elevation.
Description
Calochortus tiburonensis is a perennialPerennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...
growing from a bulb
Bulb
A bulb is a short stem with fleshy leaves or leaf bases. The leaves often function as food storage organs during dormancy.A bulb's leaf bases, known as scales, generally do not support leaves, but contain food reserves to enable the plant to survive adverse conditions. At the center of the bulb is...
to 10-60 cm in height with a single leaf. It produces anywhere from 2 to 7 erect flowers annually on a branching stem. The ciliate, light yellow-green petal
Petal
Petals are modified leaves that surround the reproductive parts of flowers. They often are brightly colored or unusually shaped to attract pollinators. Together, all of the petals of a flower are called a corolla. Petals are usually accompanied by another set of special leaves called sepals lying...
s are streaked with purplish-brown. When mature, ovaries form capsule
Capsule (fruit)
In botany a capsule is a type of simple, dry fruit produced by many species of flowering plants. A capsule is a structure composed of two or more carpels that in most cases is dehiscent, i.e. at maturity, it splits apart to release the seeds within. A few capsules are indehiscent, for example...
full of small, dark brown seeds.
Conservation
The plant was federally listed as a threatened species in 1995. It is considered threatened due to loss of surrounding habitat to recreational activities, to competition from invasive plant speciesInvasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
, to its proximity to a dense population center, and to its confinement to a single population of plants. The population grows on land owned by the Marin County Open Space District, an area previously owned and preserved by The Nature Conservancy
The Nature Conservancy
The Nature Conservancy is a US charitable environmental organization that works to preserve the plants, animals, and natural communities that represent the diversity of life on Earth by protecting the lands and waters they need to survive....
. It was first brought to the attention of science in 1971, and was described to science in 1973. It is protected along with a number of other rare 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 endemics that grow on and around Ring Mountain.
The plant has probably always been rare and limited to its current distribution on the Ring Mountain outcrop. A 1991 estimate placed the total population size at about 40,000 individuals. While the land is protected, the flora upon it are still vulnerable to events such as wildfire
Wildfire
A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, squirrel fire, vegetation fire, veldfire, and wilkjjofire may be used to describe the same...
s or drought
Drought
A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region...
, and to damage from hikers
Hiking
Hiking is an outdoor activity which consists of walking in natural environments, often in mountainous or other scenic terrain. People often hike on hiking trails. It is such a popular activity that there are numerous hiking organizations worldwide. The health benefits of different types of hiking...
, cyclists
Mountain bike
A mountain bike or mountain bicycle is a bicycle created for off-road cycling. This activity includes traversing of rocks and washouts, and steep declines,...
, vandals
Vandalism
Vandalism is the behaviour attributed originally to the Vandals, by the Romans, in respect of culture: ruthless destruction or spoiling of anything beautiful or venerable...
, and wildflower collectors.
Sources
- Calochortus tiburonensis. USDA, NRCS. 2006. The PLANTS Database, Version 3.5. Data compiled from various sources by Mark W. Skinner. National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
- Flora of North America
- Photo gallery