Polygonum hickmanii
Encyclopedia
Polygonum hickmanii is a rare species of flowering plant in the buckwheat family
known by the common names Scotts Valley polygonum and Hickman's knotweed. It is endemic to Santa Cruz County, California
, where it is known from only two occurrences in the Scotts Valley
. It grows on coastal prairie
on mudstone
and sandstone
substrates, in an area known for its spring wildflowers. The small plant was first noted in 1990 and described as a new species in 1995. The plant is a federally listed endangered species
.
This is a small annual plant forming compact patches on the ground, its stem growing no more than about 5 centimeters tall. It is lined with linear leaves especially near the tips of the branches, and has a cylindrical, shreddy ochrea
. Solitary flowers occur in the leaf axils. They are only 2 or 3 millimeters long and white or pink-tinged in color. The eight tiny stamen
s are tipped with orange-pink anthers.
Threats to this species include proposed development
in its small, patchy habitat and the invasion of non-native plants
.
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...
known by the common names Scotts Valley polygonum and Hickman's knotweed. It is endemic to Santa Cruz County, California
Santa Cruz County, California
Santa Cruz County is a county located on the Pacific coast of the U.S. state of California, on the California Central Coast. The county forms the northern coast of the Monterey Bay. . As of the 2010 U.S. Census, its population was 262,382. The county seat is Santa Cruz...
, where it is known from only two occurrences in the Scotts Valley
Scotts Valley, California
Scotts Valley is a small city in Santa Cruz County, California, United States, about thirty miles south of downtown San Jose and six miles north of Monterey Bay, in the upland slope of the Santa Cruz Mountains. As of the 2010 census, the city population was 11,580...
. It grows on coastal prairie
California coastal prairie
California coastal prairie, also known as northern coastal grassland, is a grassland plant community of California and Oregon in the Temperate grasslands, savannas, and shrublands Biome...
on mudstone
Mudstone
Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...
and 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,...
substrates, in an area known for its spring wildflowers. The small plant was first noted in 1990 and described as a new species in 1995. The plant 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...
.
This is a small annual plant forming compact patches on the ground, its stem growing no more than about 5 centimeters tall. It is lined with linear leaves especially near the tips of the branches, and has a cylindrical, shreddy ochrea
Ochrea
Ochrea, commonly spelled ocrea, is a structure formed of stipules fused into a sheath surrounding the stem. It is a diagnostic character in the Polygonaceae.In palms it denotes an extension of the leaf sheath beyond the petiole insertion....
. Solitary flowers occur in the leaf axils. They are only 2 or 3 millimeters long and white or pink-tinged in color. The eight tiny stamen
Stamen
The stamen is the pollen producing reproductive organ of a flower...
s are tipped with orange-pink anthers.
Threats to this species include proposed development
Urban planning
Urban planning incorporates areas such as economics, design, ecology, sociology, geography, law, political science, and statistics to guide and ensure the orderly development of settlements and communities....
in its small, patchy habitat and the invasion of non-native plants
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...
.