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

Brassicaceae

Brassicaceae, a medium sized and economically important family of flowering plants , are informally known as the mustards, mustard flowers, the crucifers or the cabbage family....

 known by the common name Kneeland Prairie penny-cress. It is endemic to California, where it is known from only one stretch of grassland in Humboldt County

Humboldt County, California

Humboldt County is a county in the U.S. state of California, located on the far North Coast 200 miles north of San Francisco. According to 2010 Census Data, the county’s population was 134,623...

. It is threatened by development. 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 taxonomy

Biological classification

Biological classification, or scientific classification in biology, is a method to group and categorize organisms by biological type, such as genus or species. Biological classification is part of scientific taxonomy....

 of this species is uncertain. Authors call it Thlaspi californicum, Thlaspi montanum var. californicum, Noccaea californica, and Noccaea fendleri ssp. californica, and there are other synonyms

Synonym (taxonomy)

In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...

.

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

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...

 is a raceme

Raceme

A raceme is a type of inflorescence that is unbranched and indeterminate and bears pedicellate flowers — flowers having short floral stalks called pedicels — along the axis. In botany, axis means a shoot, in this case one bearing the flowers. In a raceme, the oldest flowers are borne...

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

Silique

A silique or siliqua is a fruit of 2 fused carpels with the length being more than three times the width. The outer walls of the ovary usually separate when ripe, leaving a persistent partition...

. The plant often reproduces vegetatively

Vegetative reproduction

Vegetative reproduction is a form of asexual reproduction in plants. It is a process by which new individuals arise without production of seeds or spores...

 by cloning

Cloning

Cloning in biology is the process of producing similar populations of genetically identical individuals that occurs in nature when organisms such as bacteria, insects or plants reproduce asexually. Cloning in biotechnology refers to processes used to create copies of DNA fragments , cells , or...

.

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

Kneeland Airport

Kneeland Airport is a public airport operated by Humboldt County and located 10 miles southeast of the central business district of Eureka, USA. The airport is co-located with a California Dept. of Forestry Helitack Station. Located on a mountain ridge line at over 2,700 ft...

 on the Kneeland Prairie near Eureka

Eureka, California

Eureka is the principal city and the county seat of Humboldt County, California, United States. Its population was 27,191 at the 2010 census, up from 26,128 at the 2000 census....

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

Outcrop

An 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 deposits are covered by a mantle of soil and vegetation and cannot be...

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

Serpentine soil

A serpentine soil is derived from ultramafic rocks, in particular serpentinite, a rock formed by the hydration and metamorphic transformation of ultramafic rock from the Earth's mantle....

s of the local landscape.

This plant is threatened by development at the airport and other facilities nearby, including roads and a helitack

Helitack

Helitack refers to "helicopter-delivered fire resources", and is the system of managing and using helicopters and their crews to perform aerial firefighting and other firefighting duties, primarily initial attack on wildfires...

 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

Habitat fragmentation as the name implies, describes the emergence of discontinuities in an organism's preferred environment , causing population fragmentation...

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

Parking lot

A parking lot , also known as car lot, is a cleared area that is intended for parking vehicles. Usually, the term refers to a dedicated area that has been provided with a durable or semi-durable surface....

, may reduce the amount of suitable habitat further.

External links

• Thlaspi californicum. CalPhotos.