Endangered Species in Santa Cruz County - Plants


Scotts Valley Polygonum

Scotts Valley Polygonum

Scientific Name: Polygonum hickmanii

Status: E

The Scotts Valley Polygonum (also known as Hickman's Knotweed) is a small, erect, taprooted annual in the buckwheat family. It grows from 2 to 5 cm. (1 to 2 in.) tall, and can be either single-stemmed or profusely branching near the base. The single white flowers are found in the axils of the bracteal leaves.

Habitat: Occurs with other small annual herbs in patches within annual grasslands. These "wildflower field" patches are generally underlain by shallow, well-drained soils; this species occurs on gently sloping to nearly level shallow soils over outcrops of Santa Cruz mudstone and Purisima sandstone. It is found near the center of the patches where the soil is shallowest and often has a consolidated, crusty surface texture; other species are sparse in patch centers. Only four colonies are known from two sites about one mile apart at the northern end of Scotts Valley, CA: its occupied habitat comprises less than one acre total.

Threats: Alteration of habitat by urban development, displacement by nonnative grasses, and the increased chance of extinction due to the small numbers of individuals and limited amount of habitat.

To Learn More:

  • Calflora
    Searchable database featuring all 8375 currently-recognized vascular plants in California, including 20000 photographs.
  • NatureServe - Explorer
    Enter species name in the search box to access a detailed description of that species, along with its habitat, current conservation status, ecological and distribution data, with citations to relevant management reports.
  • U.S. Fish & Wildlife Service
    Documents describing protection for this species under the Endangered Species Act. General information about the species as well as plans protect it and and assist in its recovery.
  • Species Account
    Excerpts from U.S. Fish and Wildlife Service documents available at the Central Branch Library

Last updated by teeterj on Oct. 27, 2011

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PCH — Critical habitat which has been proposed

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