''Deinandra conjugens'' (

syn. The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently. * In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linnae ...

''Hemizonia conjugens'') is a rare species of flowering plant in the family

Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...

known by the common names Otay tarplant and Otay tarweed. It is native to a small section of far northern

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

, its range extending north into

San Diego County, California San Diego County (), officially the County of San Diego, is a county in the southwestern corner of the U.S. state of California. As of the 2020 census, the population was 3,298,634, making it California's second-most populous county and the fi ...

, in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

. One isolated population has been reported from the hills east of

Cayucos Cayucos (Spanish for "Canoe") is an unincorporated coastal town in San Luis Obispo County, California, along California State Route 1 between Cambria to the north and Morro Bay to the south. The population was 2,505 at the 2020 census, down fro ...

San Luis Obispo County San Luis Obispo County (), officially the County of San Luis Obispo, is a county on the Central Coast of California. As of the 2020 census, the population was 282,424. The county seat is San Luis Obispo. Junípero Serra founded the Mission ...

.Calflora taxon report, University of California, ''Deinandra conjugens'' (Keck) B.G. Baldwin, Otay tarplant
/ref> ''Deinandra conjugens'' is threatened by

habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

and degradation.USFWS
''Deinandra conjugens'' Five-year Review.
June 2009. It was federally listed as a threatened species in 1998.''Deinandra conjugens''.
The Nature Conservancy.

Description

''Deinandra conjugens'' is an

annual Annual may refer to: * Annual publication, periodical publications appearing regularly once per year **Yearbook ** Literary annual * Annual plant * Annual report * Annual giving * Annual, Morocco, a settlement in northeastern Morocco * Annuals (b ...

herb growing up to about in height with a solid, bristly,

gland In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure De ...

-dotted stem. The lower leaves are hairy and lobed or toothed, and measure up to about 4.5 centimeters long. The

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 formed o ...

is made up of one or more

flower heads A pseudanthium (Greek for "false flower"; ) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, compos ...

, sometimes with many heads in clusters. The underside of the head is covered in

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 or ...

with many

s. Each head has 7 to 10 yellow

ray florets The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...

no more than 6 millimeters long. Most

have three tiny lobes at the tips. The center of the head is filled with yellow

disc floret The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...

s tipped with black, dark purple or red

anthers 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 ...

. The flowers are most often

pollinated Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by wind. Pollinating agents can be animals such as insects, birds, ...

bee Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyly, monophyletic lineage within the ...

s. The fruit is an

achene An achene (; ), also sometimes called akene and occasionally achenium or achenocarp, is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and indehiscent (they do not ope ...

. The

s arising from the

s have

pappi In Asteraceae, the pappus is the modified calyx, the part of an individual floret, that surrounds the base of the corolla tube in flower. It functions as a wind-dispersal mechanism for the seeds. The term is sometimes used for similar s ...

of white scales.''Deinandra conjugens''.
Flora of North America.''Hemizonia conjugens''.
Jepson Manual. Disc achenes

germinate Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fer ...

sooner than those from

. Many

s drop into the

soil seed bank The soil seed bank is 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 lak ...

Distribution

''Deinandra conjugens'' grows in

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...

soils in several types of habitat, including

grassland A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...

and

maritime Maritime may refer to: Geography * Maritime Alps, a mountain range in the southwestern part of the Alps * Maritime Region, a region in Togo * Maritime Southeast Asia * The Maritimes, the Canadian provinces of Nova Scotia, New Brunswick, and Princ ...

and inland

coastal sage scrub Coastal sage scrub, also known as coastal scrub, CSS, or soft chaparral, is a low scrubland plant community of the California coastal sage and chaparral subecoregion, found in coastal California and northwestern coastal Baja California. It is w ...

. It tolerates some disturbance in its habitat, and low levels of

grazing In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...

and road maintenance activities such as

mowing A mower is a person or machine that cuts (mows) grass or other plants that grow on the ground. Usually mowing is distinguished from reaping, which uses similar implements, but is the traditional term for harvesting grain crops, e.g. with reapers ...

are probably beneficial. Most of the known occurrences of ''Deinandra conjugens'' are in

San Diego County San Diego County (), officially the County of San Diego, is a county in the southwestern corner of the U.S. state of California. As of the 2020 census, the population was 3,298,634, making it California's second-most populous county and the fi ...

in the

. Most of them are located in the southern part of the county in areas such as

Otay Mesa Otay Mesa ( ) is a community in the southern section of the city of San Diego, just north of the U.S.–Mexico border. It is bordered by the Otay River Valley and the city of Chula Vista on the north; Interstate 805 and the neighborhoods of Oc ...

and Proctor Valley.''Deinandra conjugens'' (Otay Tarplant).
City of San Diego Rare Plant Monitoring Report, 2005. The

city of San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the eighth most populous city in the United States ...

has a conservation plan for this species and monitors it. There are about 34 to 37 occurrences remaining; some known occurrences are thought to have been

extirpated Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...

since the plant was federally listed.

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 reserve A nature reserve (also known as a wildlife refuge, wildlife sanctuary, biosphere reserve or bioreserve, natural or nature preserve, or nature conservation area) is a protected area of importance for flora, fauna, or features of geological or ...

s. Many are protected under a

San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the List of United States cities by population, eigh ...

county ordinance. The

San Diego National Wildlife Refuge San Diego National Wildlife Refuge is a National Wildlife Refuge in California. It is part of the San Diego National Wildlife Refuge Complex. A variety of habitats from coastal sage scrub and chaparral to oak woodland and freshwater marsh des ...

created the Otay Tarplant Preserve, and

Caltrans The California Department of Transportation (Caltrans) is an Executive (government), executive department of the U.S. state of California. The department is part of the Government of California#State agencies, cabinet-level California State Tran ...

reserved a section of land for the plant near a busy highway. 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

are unknown. Besides outright habitat destruction, the plant is affected by several processes of habitat degradation. Introduced weeds have

invaded An invasion is a military offensive in which large numbers of combatants of one geopolitical entity aggressively enter territory owned by another such entity, generally with the objective of either: conquering; liberating or re-establishing con ...

the habitat, including brome grasses (''Bromus'' spp.), wild oats (''Avena'' spp.), and

ryegrass ''Lolium'' is a genus of tufted grasses in the bluegrass subfamily (Pooideae). It is often called ryegrass, but this term is sometimes used to refer to grasses in other genera. They are characterized by bunch-like growth habits. ''Lolium'' is ...

(''Lolium perenne'').

Off-road vehicle An off-road vehicle, sometimes referred to as an overland or adventure vehicle, is considered to be any type of vehicle which is capable of driving on and off paved or gravel surface. It is generally characterized by having large tires with dee ...

s are used on some land that contains the plant, and

trash Trash may refer to: Garbage * Garbage, unwanted or undesired waste material ** Litter, material discarded in inappropriate places ** Municipal solid waste, unwanted or undesired waste material generated in a municipal environment Arts, enter ...

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 Borders are usually defined as geographical boundaries, imposed either by features such as oceans and terrain, or by political entities such as governments, sovereign states, federated states, and other subnational entities. Political borders c ...

, and

Border Patrol A border guard of a country is a national security agency that performs border security. Some of the national border guard agencies also perform coast guard (as in Germany, Italy or Ukraine) and rescue service duties. Name and uniform In dif ...

activities affect the habitat there.

References

External links

*
Jepson eFlora (TJM2) treatment of ''Deinandra conjugens''Jepson Manual (TJM93), archived: ''Hemizonia conjugens''United States Department of Agriculture Plants Profile - ''Deinandra conjugens'' (Otay tarweed) ''Deinandra conjugens'' — Calphotos Photos Gallery, University of California
{{Taxonbar, from=Q5252460 conjugens Flora of California Flora of Baja California Natural history of the California chaparral and woodlands Natural history of the Peninsular Ranges Critically endangered flora of California Plants described in 1958