Chorizanthe orcuttiana
Encyclopedia
Chorizanthe orcuttiana is a rare small annual plant in the buckwheat
(Polygonaceae
) family. Its common name is San Diego spineflower, and it is endemic to San Diego County, California
.
The plant is diminutive, and a hand-lens is necessary for proper identification. The plant is very sensitive to temperature and precipitation
, and under drought
or hot conditions the seeds will not germinate or survive. The plant is visible anywhere from February through July during good rain year, but most years the plant is only visible from April to June. Each minute flower yields one seed. This species is octoploid and probably arose through hybridization between other Chorizanthe, perhaps C. procumbens
and C. polygonoides
.
The plant requires open habitat near the coast, such as sandstone
bluffs and openings in maritime chaparral
. About 82% to 93% of San Diego County's maritime chaparral habitat has been destroyed for development and damaged by human activity such as recreation; there are just over 3000 acre
s remaining. All the known occurrences are within five kilometers of the coastline. It grows on soils of white sand which are neutral or somewhat acidic and low in organic material. The substrates originate from iron
-rich sandstone.
The plant was believed to be extinct until it was re-discovered on Point Loma. Since its re-discovery, two additional populations were discovered on Naval Base Point Loma
, and one small population is seen infrequently at Oak Crest Park in Encinitas, California
. Lately, this population has been made up of one single plant. Most of its historic range has been developed, but due to its diminutive, infrequent nature, there is a significant chance that other undiscovered populations exist, possibly at Torrey Pines State Park, where it has been noted before. The most recent estimate for a total remaining global population is between 470 and 3000 individuals. It is a federally listed endangered species
of the United States.
The worst threat to the species is the invasion of non-native plant species
, such as ice plant (Carpobrotus edulis) and Natal grass
(Melinis repens). The plant is threatened by its limited number of populations and small population size, which increase the likelihood of extinction
; the plant may be naturally rare, but its rarity is exacerbated by other conditions, such as fire suppression.
Buckwheat
Buckwheat refers to a variety of plants in the dicot family Polygonaceae: the Eurasian genus Fagopyrum, the North American genus Eriogonum, and the Northern Hemisphere genus Fallopia. Either of the latter two may be referred to as "wild buckwheat"...
(Polygonaceae
Polygonaceae
Polygonaceae is a family of flowering plants known informally as the "knotweed family" or "smartweed family"— "buckwheat family" in the United States. The name is based on the genus Polygonum and was first used by Antoine Laurent de Jussieu in 1789 in his book, Genera Plantarum. The name refers...
) family. Its common name is San Diego spineflower, and it is endemic to San Diego County, California
San Diego County, California
San Diego County is a large county located in the southwestern corner of the US state of California. Hence, San Diego County is also located in the southwestern corner of the 48 contiguous United States. Its county seat and largest city is San Diego. Its population was about 2,813,835 in the 2000...
.
The plant is diminutive, and a hand-lens is necessary for proper identification. The plant is very sensitive to temperature and precipitation
Precipitation (meteorology)
In meteorology, precipitation In meteorology, precipitation In meteorology, precipitation (also known as one of the classes of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation...
, and under drought
Drought
A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region...
or hot conditions the seeds will not germinate or survive. The plant is visible anywhere from February through July during good rain year, but most years the plant is only visible from April to June. Each minute flower yields one seed. This species is octoploid and probably arose through hybridization between other Chorizanthe, perhaps C. procumbens
Chorizanthe procumbens
Chorizanthe procumbens is a species of flowering plant in the buckwheat family known by the common name prostrate spineflower. It is native to California and Baja California, where it grows in scrub and chaparral habitat. It is variable in appearance, up to 25 centimeters long or much shorter,...
and C. polygonoides
Chorizanthe polygonoides
Chorizanthe polygonoides is a species of flowering plant in the buckwheat family known by the common name knotweed spineflower. It is native to California and Baja California, where it grows widely scattered in many types of habitat. It is a petite plant taking a prostrate form with stems just a...
.
The plant requires open habitat near the coast, such as sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
bluffs and openings in maritime chaparral
Chaparral
Chaparral is a shrubland or heathland plant community found primarily in the U.S. state of California and in the northern portion of the Baja California peninsula, Mexico...
. About 82% to 93% of San Diego County's maritime chaparral habitat has been destroyed for development and damaged by human activity such as recreation; there are just over 3000 acre
Acre
The acre is a unit of area in a number of different systems, including the imperial and U.S. customary systems. The most commonly used acres today are the international acre and, in the United States, the survey acre. The most common use of the acre is to measure tracts of land.The acre is related...
s remaining. All the known occurrences are within five kilometers of the coastline. It grows on soils of white sand which are neutral or somewhat acidic and low in organic material. The substrates originate from iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
-rich sandstone.
The plant was believed to be extinct until it was re-discovered on Point Loma. Since its re-discovery, two additional populations were discovered on Naval Base Point Loma
Naval Base Point Loma
Located in Point Loma, a neighborhood of San Diego, California, Naval Base Point Loma was established on 1 October 1998 when Navy facilities in the Point Loma area of San Diego were consolidated under Commander, Navy Region Southwest...
, and one small population is seen infrequently at Oak Crest Park in Encinitas, California
Encinitas, California
Encinitas is a coastal beach city in San Diego County, California. Located within Southern California, it is approximately north of San Diego in North County and about south of Los Angeles. As of the 2010 census, the city had a population of 59,518, up from 58,014 at the 2000 census. Encinitas is...
. Lately, this population has been made up of one single plant. Most of its historic range has been developed, but due to its diminutive, infrequent nature, there is a significant chance that other undiscovered populations exist, possibly at Torrey Pines State Park, where it has been noted before. The most recent estimate for a total remaining global population is between 470 and 3000 individuals. It is a federally listed endangered species
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 the United States.
The worst threat to the species is the invasion of non-native plant species
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
, such as ice plant (Carpobrotus edulis) and Natal grass
Melinis repens
Melinis repens is a species of grass known by the common names rose Natal grass, or simply Natal grass, and Natal redtop. It is native to southern Africa but it is well known on other continents, including North America and Australia, as an introduced species and sometimes a noxious weed...
(Melinis repens). The plant is threatened by its limited number of populations and small population size, which increase the likelihood of extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
; the plant may be naturally rare, but its rarity is exacerbated by other conditions, such as fire suppression.