Lasthenia conjugens
Encyclopedia
Lasthenia conjugens, commonly known as Contra Costa goldfields, is an endangered species
of wildflower
endemic
to a limited range within the San Francisco Bay Area
of the state of California
, USA
. Specifically this rare species
occurs in Napa
, Santa Barbara
, Solano
, Contra Costa
, Santa Clara
, Monterey
and Alameda Counties
. This annual herb
typically flowers from March through June, and its colonies grow in vernal pool
habitat
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
, principally Napa and Solano Counties, 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 San Francisco Bay Area
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.
ly lobed. Inflorescence
s appear in the form of solitary head
s, with twelve to eighteen phyllaries
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
. 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 tips are linear to somewhat ovate. Style tips are triangular. The corollae are typically five-lobed. Style tips may be triangular or round, but typically hair-tufted. The glabrous club-shaped fruits are less than 1.5 millimeters across, black or gray in color, absent a pappus
structure. The species is cross-pollinated. According to Greene, the chromosome characteristic is: 2n=12.
for fertilization, and dispersal of seed is largely by gravity. 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
, are extremely efficient pollinators of L. conjugens, since it was the only insect family to visit the restoration colonies in significant numbers.
, more southerly parts of the San Francisco Bay Area
and parts of the South Coast. Moreover, the U.S. Fish and Wildlife Service alludes to historic populations in Contra Costa County and Santa Clara County. More specifically another source defines the extended historic San Francisco Bay Area range to have extended from Richmond
to Palo Alto
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
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...
of wildflower
Wildflower
A wildflower is a flower that grows wild, meaning it was not intentionally seeded or planted. Yet "wildflower" meadows of a few mixed species are sold in seed packets. The term "wildflower" has been made vague by commercial seedsmen who are interested in selling more flowers or seeds more...
endemic
Endemic (ecology)
Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to the...
to a limited range within 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 the state 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...
, USA
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. Specifically this rare species
Rare species
A rare species is a group of organisms that are very uncommon or scarce. This designation may be applied to either a plant or animal taxon, and may be distinct from the term "endangered" or "threatened species" but not "extinct"....
occurs in Napa
Napa County, California
Napa County is a county located north of the San Francisco Bay Area in the U.S. state of California. It is coterminous with the Napa, California, Metropolitan Statistical Area. As of 2010 the population is 136,484. The county seat is Napa....
, Santa Barbara
Santa Barbara County, California
Santa Barbara County is a county located in the southern portion of the U.S. state of California, on the Pacific coast. As of 2010 the county had a population of 423,895. The county seat is Santa Barbara and the largest city is Santa Maria.-History:...
, Solano
Solano County, California
Solano County is a county located in Bay-Delta region of the U.S. state of California, about halfway between San Francisco and Sacramento and is one of the nine San Francisco Bay Area counties. The county's population was reported by the U.S. Census to be 413,344 in 2010...
, Contra Costa
Contra Costa County, California
Contra Costa County is a primarily suburban county in the San Francisco Bay Area of the U.S. state of California. As of the 2010 census, it had a population of 1,049,025...
, Santa Clara
Santa Clara County, California
Santa Clara County is a county located at the southern end of the San Francisco Bay Area in the U.S. state of California. As of 2010 it had a population of 1,781,642. The county seat is San Jose. The highly urbanized Santa Clara Valley within Santa Clara County is also known as Silicon Valley...
, Monterey
Monterey County, California
Monterey County is a county located on the Pacific coast of the U.S. state of California, its northwestern section forming the southern half of Monterey Bay. The northern half of the bay is in Santa Cruz County. As of 2010, the population was 415,057. The county seat and largest city is Salinas...
and Alameda Counties
Alameda County, California
Alameda County is a county in the U.S. state of California. It occupies most of the East Bay region of the San Francisco Bay Area. As of the 2010 census it had a population of 1,510,271, making it the 7th most populous county in the state...
. This annual herb
Herb
Except in botanical usage, an herb is "any plant with leaves, seeds, or flowers used for flavoring, food, medicine, or perfume" or "a part of such a plant as used in cooking"...
typically flowers from March through June, and its colonies grow in vernal pool
Vernal pool
Vernal pools, also called vernal ponds or ephemeral pools, are temporary pools of water. They are usually devoid of fish, and thus allow the safe development of natal amphibian and insect species...
habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
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
Sacramento Valley
The Sacramento Valley is the portion of the California Central Valley that lies to the north of the San Joaquin-Sacramento Delta in the U.S. state of California. It encompasses all or parts of ten counties.-Geography:...
, principally Napa and Solano Counties, 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
North Coast, California
The North Coast of California is a region which commonly includes Marin, Sonoma, Mendocino, Humboldt, and Del Norte counties...
, Sacramento Valley, and 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...
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 leaves, of length of approximately eight centimeters, are entire to pinnatePinnate
Pinnate is a term used to describe feather-like or multi-divided features arising from both sides of a common axis in plant or animal structures, and comes from the Latin word pinna meaning "feather", "wing", or "fin". A similar term is pectinate, which refers to a comb-like arrangement of parts...
ly lobed. 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...
s appear in the form of solitary head
Head (botany)
The capitulum is considered the most derived form of inflorescence. Flower heads found outside Asteraceae show lesser degrees of specialization....
s, with twelve to eighteen 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...
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
Sphere
A sphere is a perfectly round geometrical object in three-dimensional space, such as the shape of a round ball. Like a circle in two dimensions, a perfect sphere is completely symmetrical around its center, with all points on the surface lying the same distance r from the center point...
. The receptacle presents as dome-shaped or obconic
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 case of fungi the designation is often made to the...
. 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 tips are linear to somewhat ovate. Style tips are triangular. The corollae are typically five-lobed. Style tips may be triangular or round, but typically hair-tufted. The glabrous club-shaped fruits are less than 1.5 millimeters across, black or gray in color, absent a 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...
structure. The species is cross-pollinated. According to Greene, the chromosome characteristic is: 2n=12.
Ecology
Lasthenia conjugens relies upon insect pollinationPollinator
A pollinator is the biotic agent that moves pollen from the male anthers of a flower to the female stigma of a flower to accomplish fertilization or syngamy of the female gamete in the ovule of the flower by the male gamete from the pollen grain...
for fertilization, and dispersal of seed is largely by gravity. Studies in Solano County natural and restoration habitats
Restoration ecology
-Definition:Restoration ecology is the scientific study and practice of renewing and restoring degraded, damaged, or destroyed ecosystems and habitats in the environment by active human intervention and action, within a short time frame...
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
Sciaridae
Sciaridae is 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 studied of the large Diptera families, probably due to the small...
, are extremely efficient pollinators of L. conjugens, since it was the only insect family to visit the restoration colonies in significant numbers.
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 Sacramento ValleySacramento Valley
The Sacramento Valley is the portion of the California Central Valley that lies to the north of the San Joaquin-Sacramento Delta in the U.S. state of California. It encompasses all or parts of ten counties.-Geography:...
, more southerly parts of 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...
and parts of the South Coast. Moreover, the U.S. Fish and Wildlife Service alludes to historic populations in Contra Costa County and Santa Clara County. More specifically another source defines the extended historic San Francisco Bay Area range to have extended from Richmond
Richmond, California
Richmond is a city in western Contra Costa County, California, United States. The city was incorporated on August 7, 1905. It is located in the East Bay, part of the San Francisco Bay Area. It is a residential inner suburb of San Francisco, as well as the site of heavy industry, which has been...
to Palo Alto
Palo Alto, California
Palo Alto is a California charter city located in the northwest corner of Santa Clara County, in the San Francisco Bay Area of California, United States. The city shares its borders with East Palo Alto, Mountain View, Los Altos, Los Altos Hills, Stanford, Portola Valley, and Menlo Park. It is...
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
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
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.
See also
- Vernal poolVernal poolVernal pools, also called vernal ponds or ephemeral pools, are temporary pools of water. They are usually devoid of fish, and thus allow the safe development of natal amphibian and insect species...
- List of early spring flowers
- List of late spring flowers
- List of early summer flowers