''Lasthenia conjugens'', commonly known as Contra Costa goldfields, is an

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

wildflower A wildflower (or wild flower) is a flower that grows in the wild, meaning it was not intentionally seeded or planted. The term implies that the plant probably is neither a hybrid nor a selected cultivar that is in any way different from the ...

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to a limited range within the

San Francisco Bay Area The San Francisco Bay Area, often referred to as simply the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. The Bay Area is defined by the Association of Bay Area G ...

of the state of

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

, USA. Specifically this rare species occurs in Napa, Santa Barbara, Solano, Contra Costa, Santa Clara,

Monterey Monterey (; es, Monterrey; Ohlone: ) is a city located in Monterey County on the southern edge of Monterey Bay on the U.S. state of California's Central Coast. Founded on June 3, 1770, it functioned as the capital of Alta California under bot ...

and Alameda Counties.2004 Distribution map showing occurrences of ''Lasthenia conjugens''
/ref> This annual

herb In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicina ...

typically flowers from March through June, and its colonies grow in

vernal pool Vernal pools, also called vernal ponds or ephemeral pools, are seasonal pools of water that provide habitat for distinctive plants and animals. They are considered to be a distinctive type of wetland usually devoid of fish, and thus allow the safe ...

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s at elevations not exceeding 100 meters above sea level. ''The Jepson Manual'' notes that the present distribution is limited to the deltaic

Sacramento Valley , photo =Sacramento Riverfront.jpg , photo_caption= Sacramento , map_image=Map california central valley.jpg , map_caption= The Central Valley of California , location = California, United States , coordinates = , boundaries = Sierra Nevada (ea ...

, principally Napa and Solano Counties,''The Jepson Manual'', University of California Press 1993
/ref> but the historic range of ''L. conjugens'' is known to be significantly wider. In any case, historically the range has included parts of the North Coast, Sacramento Valley, and

Sensitive Species of the San Francisco Bay Area
/ref> as well as the South Coast. Alternatively and less frequently this taxon has been referred to as ''Baeria fremontii var. conjugens''. Even though this plant is found almost exclusively in vernal pools, its behavior in controlled experiments indicates it prefers less than complete inundation. This implies that the plant actually prefers a theoretically drier environment, but is merely less successful than its competitors in surviving in drier (non-inundation) climate regimes.

Description

''Lastenia conjugens'' is an herb whose stems are simple or freely branched and erect, attaining a height of less than 40 centimeters. Their

glabrous Glabrousness (from the Latin '' glaber'' meaning "bald", "hairless", "shaved", "smooth") is the technical term for a lack of hair, down, setae, trichomes or other such covering. A glabrous surface may be a natural characteristic of all or part of ...

leaves, of length of approximately eight centimeters, are entire to

pinnate Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, an ...

ly lobed.

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. Morphologically, it is the modified part of the shoot of seed plants where flowers are forme ...

s appear in the form of solitary

head A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals ...

s, with twelve to eighteen

phyllaries In botanical terminology, a phyllary, also known an involucral bract or tegule, is a single bract of the involucre of a composite flower. The involucre is the grouping of bracts together. Phyllaries are reduced leaf-like structures that form one o ...

fused at one third to less than mid length, a distinguishing hallmark for identification of this species. An involucre structure measures six to ten millimeters and may be somewhat hemispheric. The receptacle presents as dome-shaped or

obconic In botany, an obconic is an inverted cone shape. The term is most frequently applied to certain fruit or hypanthium structures with the apical end attached to the stem; however, less frequently the usage may apply to the pistil structure. In the ca ...

. The yellow ray flowers may number six to thirteen petals, and the five to ten millimeter ligules are yellow as well. The yellow disk flowers are numerous, and

anther The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filam ...

tips are linear to somewhat ovate. Style tips are triangular. The

corolla Corolla may refer to: *Corolla (botany), the petals of a flower, considered as a unit *Toyota Corolla, an automobile model name *Corolla (headgear) A ''corolla'' is an ancient headdress in the form of a small circlet or crown.pappus structure. The species is cross-pollinated. According to Greene, the chromosome characteristic is: 2n=12.

Ecology

''Lasthenia conjugens'' relies upon

insect pollination Entomophily or insect pollination is a form of pollination whereby pollen of plants, especially but not only of flowering plants, is distributed by insects. Flowers pollinated by insects typically advertise themselves with bright colours, some ...

for fertilization, and dispersal of seed is largely by

gravity In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...

. In undisturbed habitats, this and other species of ''Lasthenia'' are pollinated by specialist bee species, primarily in the genus ''

Andrena ''Andrena'' is a genus of bees in the family Andrenidae. With over 1,500 species, it is one of the largest genera of animals. It is a strongly monophyletic group that is difficult to split into more manageable divisions; currently, ''Andrena'' is ...

''. Studies in Solano County natural and restoration habitats have shown variability between visitation rates to the two types of colonies; however, plant propagation rates were found to be similar between natural colonies and introduced ones, implying pollination is not a limiting factor of propagation. An alternative conclusion is that members of one particular insect family,

Sciaridae The Sciaridae are a family of flies, commonly known as dark-winged fungus gnats. Commonly found in moist environments, they are known to be a pest of mushroom farms and are commonly found in household plant pots. This is one of the least studie ...

, are also efficient pollinators of ''L. conjugens'', since it was the only insect family to visit the restoration colonies in significant numbers (the specialist bees are absent from these areas).

Conservation

The population trend for ''L. conjugens'' is one of declining numbers as well as shrinking range. According to Jepson, the historic range includes areas not in the present range: parts of the North Coast, more eastern reaches of the

, more southerly parts of the

and parts of the South Coast. Moreover, the U.S. Fish and Wildlife Service alludes to historic populations in

Contra Costa County ) of the San Francisco Bay , subdivision_type = Country , subdivision_name = United States , subdivision_type1 = State , subdivision_name1 = California , subdivision_type2 ...

and

Santa Clara County Santa Clara County, officially the County of Santa Clara, is the sixth-most populous county in the U.S. state of California, with a population of 1,936,259, as of the 2020 census. Santa Clara County and neighboring San Benito County together f ...

. More specifically another source defines the extended historic San Francisco Bay Area range to have extended from

Richmond Richmond most often refers to: * Richmond, Virginia, the capital of Virginia, United States * Richmond, London, a part of London * Richmond, North Yorkshire, a town in England * Richmond, British Columbia, a city in Canada * Richmond, California, ...

Palo Alto Palo Alto (; Spanish for "tall stick") is a charter city in the northwestern corner of Santa Clara County, California, United States, in the San Francisco Bay Area, named after a coastal redwood tree known as El Palo Alto. The city was estab ...

By the year 1995 the populations of ''L. conjugens'' had declined to the point where there were only five colonies extant, all of which were within Napa and Solano Counties. Contra Costa goldfields has been studied extensively with regard to genetic diversity of colonies. Some early findings were that repeated seedings in restoration colonies enhanced the resultant population of ''Lasthenia conjugens'' and hence ultimate survival. The subsequent finding has been made that genetic diversity has been able to be replicated for introduced colonies in a restoration environment, implying favorable long-term stability and viability for introduced colonies. In addition to the federal status as an endangered species it gained on June 18, 1997, ''Lasthenia conjugens'' is acknowledged and protected under the Solano County ''Habitat Conservation Plan'' (HCP). The Solano County Habitat Conservation Plan encourages corridor preservation among vernal pool habitats, which are essential for this species' survival; in addition the HCP states the importance of recognizing genetic differences amongst various colonies of ''L. conjugens'' in order to protect the total species genetic diversity. Contra Costa goldfields is not listed by the State of California as ''endangered''.Endangered Species Recovery Plan

References

External links

* ttp://ecos.fws.gov/species_profile/servlet/gov.doi.species_profile.servlets.SpeciesProfile?spcode=Q122 U.S. Fish and Wildlife Service listing details for the endangered species ''Lasthenia conjugens''* {{Taxonbar, from=Q6494954 conjugens Endemic flora of California Natural history of Contra Costa County, California Critically endangered flora of California