Deinandra conjugens

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Deinandra conjugens
Deinandra conjugens.jpg
Status TNC G1.svg
Critically Imperiled  (NatureServe)
Scientific classification
Kingdom:
Plantae
(unranked):
Angiosperms
(unranked):
Eudicots
(unranked):
Asterids
Order:
Asterales
Family:
Asteraceae
Subfamily:
Asteroideae
Tribe:
Heliantheae
Genus:
Deinandra
Species:
D. conjugens
Binomial name
Deinandra conjugens
Synonyms [1]

Hemizonia conjugens D.D.Keck

Deinandra conjugens (syn. Hemizonia conjugens) is a rare species of flowering plant in the aster family known by the common names Otay tarplant and Otay tarweed. It is native to a small section of far northern Baja California in Mexico, its range extending north into San Diego County, California, in the United States. One isolated population has been reported from the hills east of Cayucos in San Luis Obispo County. [2]

Contents

Deinandra conjugens is threatened by habitat destruction and degradation. [3] It was federally listed as a threatened species in 1998. [4]

Description

Deinandra conjugens is an annual herb growing up to about 0.5 metres (1.6 ft) in height with a solid, bristly, gland-dotted stem. The lower leaves are hairy and lobed or toothed, and measure up to about 4.5 centimeters long. [5]

The inflorescence is made up of one or more flower heads, sometimes with many heads in clusters. The underside of the head is covered in phyllaries with many glands. Each head has 7 to 10 yellow ray florets no more than 6 millimeters long. Most ray florets have three tiny lobes at the tips. The center of the head is filled with yellow disc florets tipped with black, dark purple or red anthers. The flowers are most often pollinated by bees. [3] [5]

The fruit is an achene. The achenes arising from the disc florets have pappi of white scales. [5] [6] Disc achenes germinate sooner than those from ray florets. Many achenes drop into the soil seed bank. [3]

Distribution

Deinandra conjugens grows in clay soils in several types of habitat, including grassland and maritime and inland coastal sage scrub. [3] It tolerates some disturbance in its habitat, and low levels of grazing and road maintenance activities such as mowing are probably beneficial. [3] [4]

Most of the known occurrences of Deinandra conjugens are in San Diego County in the United States. Most of them are located in the southern part of the county in areas such as Otay Mesa and Proctor Valley. [7] The city of San Diego has a conservation plan for this species and monitors it. [7] There are about 34 to 37 occurrences remaining; some known occurrences are thought to have been extirpated since the plant was federally listed. [3]

Conservation

The region in which the plant lives is heavily impacted by development and other processes and exists now in a fragmented state. 70% of the plant's habitat within its range has been destroyed. Much of the territory previously threatened by development has been conserved within a number of nature reserves. Many are protected under a San Diego county ordinance. The San Diego National Wildlife Refuge created the Otay Tarplant Preserve, and Caltrans reserved a section of land for the plant near a busy highway. [3] While many California populations are now protected, there are still many that are in danger of destruction. The status and distribution of this plant within Mexico are unknown. [3]

Besides outright habitat destruction, the plant is affected by several processes of habitat degradation. Introduced weeds have invaded the habitat, including brome grasses (Bromus spp.), wild oats (Avena spp.), and ryegrass (Lolium perenne). [7] Off-road vehicles are used on some land that contains the plant, and trash dumping has been known to occur. The maintenance of rural roads that lead to utility outposts may affect the land. Many occurrences are near the international border, and Border Patrol activities affect the habitat there. [4]

Related Research Articles

<i>Hemizonia</i> Genus of flowering plants

Hemizonia is a genus of plants in the daisy family (Asteraceae). They are known generally as tarweeds, although some tarweeds belong to other genera, such as Madia and Deinandra. Furthermore, Hemizonia is currently being revised; some species may be segregated into new genera.

<i>Hemizonia congesta</i> Species of flowering plant

Hemizonia congesta, known by the common name hayfield tarweed, is a species of flowering plant in the daisy family, native to western North America.

<i>Deinandra</i> Genus of flowering plants

Deinandra is a genus of tarweeds in the daisy family. Such a genus is not recognized as distinct by all authorities; its species are often treated as members of genus Hemizonia.

<i>Holocarpha heermannii</i> Species of flowering plant

Holocarpha heermannii is a species of flowering plant in the aster family known by the common name Heermann's tarweed. It is endemic to California.

<i>Holocarpha virgata</i> Species of flowering plant

Holocarpha virgata is a species of flowering plant in the aster family known by the common names yellowflower tarweed, pitgland tarweed, and narrow tarplant.

<i>Madia gracilis</i>

Madia gracilis is a species of flowering plant in the aster family known by the common names grassy tarweed, slender tarweed, and gumweed madia.

<i>Anisocarpus madioides</i> Species of flowering plant

Anisocarpus madioides is a North American species of flowering plant in the aster family known by the common name woodland madia.

<i>Madia sativa</i> Species of plant

Madia sativa, known by the common names coast tarweed and Chilean tarweed, is a species of flowering plant in the aster family found in parts of western North and South America.

Deinandra bacigalupii is a rare species of flowering plant in the aster family, Asteraceae, known by the common names Livermore tarplant and Livermore moonshine. It is endemic to Alameda County, California, where there are only about five known occurrences around Livermore. It grows in open areas with alkali soils, such as alkali sinks and meadows. This plant was previously included within Deinandra increscens ssp. increscens, but it was separated and elevated to species level in 1999.

Deinandra increscens is a species of flowering plant in the aster family known by the common name grassland tarweed. It is endemic to California, where it has been found primarily in Monterey, San Luis Obispo and Santa Barbara Counties. A few isolated populations have been reported from Kern and Merced Counties, but these are from urban areas and probably represent cultivated specimens.

<i>Deinandra fasciculata</i> Species of flowering plant

Deinandra fasciculata, known by the common names clustered tarweed and fascicled spikeweed, is a species of flowering plant in the daisy family native to western North America.

<i>Deinandra minthornii</i> Species of flowering plant

Deinandra minthornii — — is a rare California species of flowering plant in the aster family known by the common name Santa Susana tarplant, or Santa Susana tarweed. It is an endangered species, listed as a Threatened species by the California Department of Fish and Game, as Imperiled under the California Endangered Species Act—CESA, and on the California Native Plant Society Inventory of Rare and Endangered Plants of California.

Deinandra mohavensis is a species of flowering plant in the aster family known by the common name Mojave tarplant, or Mojave tarweed.

Deiandra arida, also called Red Rock tarplant, is a rare California annual plant in the.

Deinandra greeneana is a rare North American species of plants in the tarweed tribe within the.

Deinandra streetsii is a rare North American species of plants in the tarweed tribe within the.

<i>Deinandra kelloggii</i> Species of flowering plant

Deinandra kelloggii, Kellogg's spikeweed or Kellogg's tarweed, is a North American species of plants in the tarweed tribe within the. It is native to Baja California, southern and central California, and Arizona.

Deinandra pentactis, called Salinas River tarweed, is a North American species of plants in the tarweed tribe within the. It is endemic to California, found in the Coast Ranges of San Benito, Monterey, San Luis Obispo, and northern Santa Barbara Counties.

Deinandra halliana, called Hall's tarplant, is a California species of plants in the tarweed tribe within the sunflower family. It has been found in the Coast Ranges of Central California, in Monterey, Fresno, San Benito, and San Luis Obispo Counties.

Deinandra pallida, called Kern tarweed, is a California species of plants in the tarweed tribe within the sunflower family. It has been found in the Coast Ranges, southern San Joaquin Valley, and Sierra Nevada foothills in Kern, Los Angeles, Santa Barbara, San Luis Obispo, Tulare, and Kings Counties. Isolated populations have been reported from farther north in Tuolumne County and northwestern Fresno County.

References

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