''Plagiobothrys strictus'' is a rare species of flowering plant in the borage family known by the common name Calistoga popcornflower. 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 ...

Napa County, California Napa County () is a county north of San Pablo Bay located in the northern portion of the U.S. state of California. As of the 2020 census, the population was 138,019. The county seat is the City of Napa. Napa County was one of the original co ...

, where it is known from only two small locations near Calistoga.

Description

This is an annual herb growing erect 10 to 40 centimeters tall. It is mostly hairless except for the

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coined b ...

s, which have some rough hairs. The leaves are located along the stem and measure 4 to 9 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 paired branches bearing several five-lobed white flowers each about half a centimeter wide. The fruit is a ribbed nutlet 1 or 2 millimeters long.

Distribution and habitat

It grows in wet grassy

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

kept moist by runoff from

hot spring A hot spring, hydrothermal spring, or geothermal spring is a spring produced by the emergence of geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow bodies of magma (molten rock) or by circ ...

s and pools. The combined area of land containing the two populations was estimated to be less than 80 square meters in 1990.USFWS
Endangered and threatened wildlife and plants; Determination of endangered status for nine plants from the grasslands or mesic areas of the Central Coast of California.
''Federal Register'' October 22, 1997. The species is threatened by the disturbance of its

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 ...

habitat; both populations are on privately owned, unprotected land; one of these is situated next to a small

airport An airport is an aerodrome with extended facilities, mostly for commercial air transport. Airports usually consists of a landing area, which comprises an aerially accessible open space including at least one operationally active surface ...

Endangered status

''Plagiobothrys strictus'' 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.

References

External links

Jepson Manual Treatment
strictus Endemic flora of California Natural history of the California chaparral and woodlands Natural history of Napa County, California Endemic flora of the San Francisco Bay Area {{Boraginoideae-stub