''Acanthoscyphus'' is a monotypic genus in the family

Polygonaceae The Polygonaceae are a family of flowering plants known informally as the knotweed family or smartweed—buckwheat family in the United States. The name is based on the genus '' Polygonum'', and was first used by Antoine Laurent de Jussieu in 1 ...

that contains the single species ''Acanthoscyphus parishii'', which is sometimes called Parish's oxytheca. This species is native and endemic to southern

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

Taxonomy

Four varieties of ''Acanthoscyphus parishii'' are recognized: *''A. p.'' var. ''abramsii'' (Abrams' oxytheca) is limited to the chaparral of mountain slopes in Santa Barbara and Ventura Counties *''A. p.'' var. ''cienegensis'' (Cienega Seca oxytheca) is known from only about six occurrences in the San Bernardino Mountains *''A. p.'' var. ''goodmaniana'' (Cushenbury oxytheca) is federally listed as an endangered species; it is known only from loose, rocky,

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

scree Scree is a collection of broken rock fragments at the base of a cliff or other steep rocky mass that has accumulated through periodic rockfall. Landforms associated with these materials are often called talus deposits. Talus deposits typically ...

on steep north-facing slopes in the San Bernardino Mountains in an area highly disturbed by limestone mining operations *''A. p.'' var. ''parishii'' is found in sandy, gravelly habitat in the Transverse Ranges

Description

It is an annual herb producing a waxy, hairless, leafless stem up to about 60 centimeters in maximum height in the spring when it is time to flower; during the winter the plant is a small rosette of oval leaves a few centimeters wide. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...

atop the stem is an array of small cymes of flowers, each enveloped in a partially fused cup of bracts tipped in spinelike awns. The flower has six hairy white or pinkish lobes.

Habitat and distribution

The species 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 else ...

to California, where it is known only from the

Transverse Ranges The Transverse Ranges are a group of mountain ranges of southern California, in the Pacific Coast Ranges physiographic region in North America. The Transverse Ranges begin at the southern end of the California Coast Ranges and lie within Santa ...

and nearby slopes of the southernmost Central Coast Ranges. It grows in dry and rocky mountain soils and has low water tolerance. It can be found at elevations of 1500-2500 meters. The species requires an annual precipitation of 30-104 centimeters and a temperature range of 26-31 degrees Celsius. The species has a growing period of 2-5 months and typically blooms between June and August.

References

External links

Jepson Manual TreatmentUSDA Plants ProfileUSFS: var. ''goodmaniana''
{{Taxonbar, from1=Q15926209, from2=Q15587534 Monotypic Polygonaceae genera Polygonaceae