Clarkia franciscana
Encyclopedia
Clarkia franciscana is a rare species of flowering plant in the evening primrose family
known by the common name Presidio clarkia. It is endemic to the San Francisco Bay Area
of California
, where it is known only from two populations at the Presidio of San Francisco
and three occurrences in Oakland
. The plant is known only from serpentine soil
s.
. The two San Francisco populations are on land which is protected from development but is affected by many other factors including invasive plant species
, trampling, and landscaping
of vegetation. The three Oakland populations are probably the remnants of one population that was fragmented by development in the heavily altered urban habitat. The largest of the three occurrences is partially protected at Redwood Regional Park
, but the other two are on privately owned property which is undergoing some development. Construction of housing is underway on the site, with less than an acre being left undeveloped as a compromise between developers and environmental advocates.
, which bears opening flowers and closed, erect flower buds. The sepal
s stay fused together as the petals bloom from one side. The small corolla is bowl-shaped, with petals up to 1.3 centimeters long and wedge-shaped with mostly flat tips. The petals are lavender-pink in color, darkest at the tips and lightening to nearly white at the base, where there is a deep red spot. The plant is self-pollinating
. The population sizes are variable from year to year; sometimes there are no plants seen at all, the seed banks
remaining dormant until conditions improve.
Onagraceae
Onagraceae, also known as the Willowherb family or Evening Primrose family, are a family of flowering plants. The family includes about 640-650 species of herbs, shrubs, and trees in 20-24 genera...
known by the common name Presidio clarkia. It is endemic to the San Francisco Bay Area
San Francisco Bay Area
The San Francisco Bay Area, commonly known as the Bay Area, is a populated region that surrounds the San Francisco and San Pablo estuaries in Northern California. The region encompasses metropolitan areas of San Francisco, Oakland, and San Jose, along with smaller urban and rural areas...
of 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 only from two populations at the Presidio of San Francisco
Presidio of San Francisco
The Presidio of San Francisco is a park on the northern tip of the San Francisco Peninsula in San Francisco, California, within the Golden Gate National Recreation Area...
and three occurrences in Oakland
Oakland, California
Oakland is a major West Coast port city on San Francisco Bay in the U.S. state of California. It is the eighth-largest city in the state with a 2010 population of 390,724...
. The plant is known only from 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.
Distribution
Clarkia franciscana is a federally listed endangered speciesEndangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
. The two San Francisco populations are on land which is protected from development but is affected by many other factors including invasive plant species
Invasive 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....
, trampling, and landscaping
Landscaping
Landscaping refers to any activity that modifies the visible features of an area of land, including:# living elements, such as flora or fauna; or what is commonly referred to as gardening, the art and craft of growing plants with a goal of creating a beautiful environment within the landscape.#...
of vegetation. The three Oakland populations are probably the remnants of one population that was fragmented by development in the heavily altered urban habitat. The largest of the three occurrences is partially protected at Redwood Regional Park
Redwood Regional Park
Redwood Regional Park is a park of the East Bay Regional Parks District in the San Francisco Bay Area. It is located in the hills east of Oakland. The park contains the largest remaining natural stand of coast redwood found in the East Bay. Redwood forests are more commonly found closer to the...
, but the other two are on privately owned property which is undergoing some development. Construction of housing is underway on the site, with less than an acre being left undeveloped as a compromise between developers and environmental advocates.
Description
The Presidio clarkia, Clarkia franciscana, is an erect annual herb growing up to about 40 centimeters in maximum height. The leaves are narrowly lance-shaped and up to about 3.5 centimeters long. The top of the stem is occupied by the inflorescenceInflorescence
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...
, which bears opening flowers and closed, erect flower buds. The sepal
Sepal
A sepal is a part of the flower of angiosperms . Collectively the sepals form the calyx, which is the outermost whorl of parts that form a flower. Usually green, sepals have the typical function of protecting the petals when the flower is in bud...
s stay fused together as the petals bloom from one side. The small corolla is bowl-shaped, with petals up to 1.3 centimeters long and wedge-shaped with mostly flat tips. The petals are lavender-pink in color, darkest at the tips and lightening to nearly white at the base, where there is a deep red spot. The plant is self-pollinating
Self-pollination
Self-pollination is a form of pollination that can occur when a flower has both stamen and a carpel in which the cultivar or species is self fertile and the stamens and the sticky stigma of the carpel contact each other in order to accomplish pollination...
. The population sizes are variable from year to year; sometimes there are no plants seen at all, the seed banks
Soil Seed Bank
The soil seed bank refers to the natural storage of seeds, often dormant, within the soil of most ecosystems. The study of soil seed banks started in 1859 when Charles Darwin observed the emergence of seedlings using soil samples from the bottom of a lake. The first scientific paper on the subject...
remaining dormant until conditions improve.