''Thlaspi californicum'' is a rare species of flowering plant in the family

Brassicaceae Brassicaceae () or (the older) Cruciferae () is a medium-sized and economically important family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous plants, while some are shrubs. The le ...

known by the common name Kneeland Prairie penny-cress. It is

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 elsew ...

to California, where it is known from only one stretch of grassland in Humboldt County. It is threatened by development. It is a federally listed

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 ...

of the United States. The

taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

of this species is uncertain. Authors call it ''Thlaspi californicum'',''Thlaspi californicum''.
''Jepson Manual Treatment''. Retrieved August 17, 2011.''Thlaspi californicum''.
''The Nature Conservancy''. Retrieved August 17, 2011.Kneeland Prairie penny-cress (''Thlaspi californicum'') 5-Year Review: Summary and Evaluation.
''USFWS'' (June 2006). Retrieved August 16, 2011. ''Thlaspi montanum'' var. ''californicum'',''Thlaspi californicum''.
''CalFlora''. Retrieved August 17, 2011. ''Noccaea californica'',''Noccaea californica''.
USDA Plants Profile. Retrieved August 17, 2011. and ''Noccaea fendleri'' ssp. ''californica'',''Noccaea fendleri'' ssp. ''californica''.
''Flora of North America''. Retrieved August 17, 2011. and there are other

synonyms A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

. This plant is a perennial herb growing roughly 10 centimeters tall, the height varying from 1 to 20 centimeters. There are spatula-shaped lower leaves a few centimeters long and a few leaves higher on the plant. 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 a

raceme A raceme ( or ) or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the s ...

of mustardlike flowers with white spoon-shaped petals just under a centimeter in length. The fruit is a

silique A silique or siliqua (plural ''siliques'' or ''siliquae'') is a type of fruit (seed capsule) having two fused carpels with the length being more than three times the width. When the length is less than three times the width of the dried fruit i ...

. The plant often reproduces vegetatively by

cloning Cloning is the process of producing individual organisms with identical or virtually identical DNA, either by natural or artificial means. In nature, some organisms produce clones through asexual reproduction. In the field of biotechnology, cl ...

. As of 2000 there was only one population of this plant. It is located adjacent to the

Kneeland Airport Kneeland Airport is a public airport operated by Humboldt County southeast of Eureka, California. Located on a mountain ridge at over above sea level, this airfield is used by general aviation aircraft, which sometimes seek an alternate airpo ...

on the Kneeland Prairie near

Eureka Eureka (often abbreviated as E!, or Σ!) is an intergovernmental organisation for research and development funding and coordination. Eureka is an open platform for international cooperation in innovation. Organisations and companies applying th ...

in Humboldt County. In the area there are three colonies growing on separate serpentine

outcrop An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. Features Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficial ...

s on the prairie. Two of the colonies are separated by the Kneeland Airport. The plant is limited to the

serpentine soil Serpentine soil is an uncommon soil type produced by weathered ultramafic rock such as peridotite and its metamorphic derivatives such as serpentinite. More precisely, serpentine soil contains minerals of the serpentine subgroup, especially anti ...

s of the local landscape. This plant is threatened by development at the airport and other facilities nearby, including roads and a

helitack Helitack crews are teams of wildland firefighters who are transported by helicopter to wildfires. Helicopters provide rapid transport, enabling helitack crews to quickly respond and assess a wildfire situation. Helitack crews may land near a wi ...

base. In the past few decades the amount of available habitat has been decreased 50% or more, possibly as much as 70%. It has also led to

habitat fragmentation Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological processes ...

as the population is bisected by the airport and the road. Planned expansion projects at the airport, including installation of a

parking lot A parking lot (American English) or car park (British English), also known as a car lot, is a cleared area intended for parking vehicles. The term usually refers to an area dedicated only for parking, with a durable or semi-durable surface ...

, may reduce the amount of suitable habitat further.

References

External links

''Thlaspi californicum''.
CalPhotos. {{Taxonbar, from=Q7786579 Brassicaceae Endemic flora of California