''Streptanthus batrachopus'' is a rare species of flowering plant in the

mustard family 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 Mt. Tamalpais jewelflower. 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 ...

Marin County, California Marin County is a County (United States), county located in the northwestern part of the San Francisco Bay Area of the U.S. state of California. As of the 2020 United States Census, 2020 census, the population was 262,231. Its county seat and ...

, where it is known only from Mt. Tamalpais and surrounding terrain. There are fewer than ten known occurrences.The Nature Conservancy
/ref> Its habitat includes

chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterranean c ...

and

coniferous forest Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All exta ...

, generally on

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 ...

Description

It is an annual herb producing a branching or unbranched stem up to about 20 centimeters in maximum height or slightly taller. Leaves near the base of the stem are oval or lance-shaped with toothed edges, somewhat fleshy in texture with a mottled pattern, and no more than 2 to 3 centimeters long. Leaves farther up the stem are lance-shaped. Flowers occur at intervals along the upper stem. Each has an urn-shaped calyx of purple or greenish

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 up to half a centimeter long. Purple or purple-streaked white petals emerge from the tip. The fruit is a straight or curving

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 ...

up to 3 centimeters in length.

References

External links

Jepson Manual TreatmentPhoto gallery
batrachopus Endemic flora of California Endemic flora of the San Francisco Bay Area Natural history of Marin County, California Critically endangered flora of California {{Brassicales-stub