Endangered Species in Santa Cruz County - Species Account


Scotts Valley Polygonum
(Polygonum hickmanii)


The information below is taken from the following publications, which are available for reference use at the Central Branch Library:


Description and Taxonomy

Scotts Valley polygonum (Polygonum hickmanii) is a recently described endemic species from Scotts Valley, Santa Cruz County, California (Hinds and Morgan 1995). Randy Morgan first noted the distinctness of this taxon in 1990 and made the type collection in 1993. The plant is a small, erect, taprooted annual in the buckwheat family (Polygonaceae). 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. The nearest location of a closely related species, P. parryi, is at Mount Hamilton about 50 miles inland. Polygonum hickmanii differs from P. parryi in its larger white flowers, longer leaves, larger anthers and achenes, and longer, straight stem sheath (Hinds and Morgan 1995).

Habitat Description

Scotts Valley polygonum occurs on gently sloping to nearly level fine-textured shallow soils over outcrops of Santa Cruz mudstone and Purisima sandstone. It occurs with the Scotts Valley spineflower and other small annual herbs in patches within isolated relictual grasslands. Elevation of the sites is from 700 to 800 feet.

Range and Distribution

Four colonies are known from two sites about one mile apart at the northern end of Scotts Valley. Occupied habitat comprises less than one acre total.1

Population Status and Current Threats

The total population of Scotts Valley polygonum has varied between 200 to 1,000 individuals over the last few years. In 1998, the total number of individuals was estimated to be on the order of 5,000 (Kathy Lyons, in litt.). On the Glenwood site, colonies occur on two parcels previously proposed for a housing development, which was never initiated, by Glenwood Homes in the early 1990's. One of these colonies has recently been included in a 4.8-acre grassland preserve as part of mitigation for current construction of a high school by the Scotts Valley School District (Lyons, in litt. 1998, Denise Duffy and Associates 1997). Several other colonies occur on adjacent land owned by Salvation Army. The Scotts Valley Water District has recently approved a recycled water distribution system, part of which will service the Glenwood area (EMC Group). One of the pipelines and access roads will come within 100 feet or less of several of the colonies on the Salvation Army parcel.

At the Polo Ranch site, a cluster of colonies is on a parcel that was recently sold by Borland International to Greystone Homes, which plans to build 67 homes on the 84.5-acre parcel. Although much of the parcel will remain in open space, most of the Scotts Valley polygonum will occur within 100 feet of proposed housing or attendant roads (City of Scotts Valley 1998). Approval for the development of Glenwood Homes and the Polo Ranch site falls under the purview of the City of Scotts Valley. Approvals for the high school and water distribution system were secured from the Scotts Valley Unified School District and the Scotts Valley Water District, respectively. Both of these agencies are exempt from local planning and zoning ordinances and regulations.

Scotts Valley polygonum is not listed by the State of California; therefore it receives no protection under the California Endangered Species Act. However, the species is given consideration during the environmental review process conducted under the California Environmental Quality Act. Although the Service is considering listing the Scotts Valley polygonum, this plant is not federally listed.

Conservation Efforts

One colony occurs on a small grassland preserve on the Scotts Valley Unified School District property and will be subject to a monitoring and management plan (Biotic Resources Group 1998).

Needed Conservation Measures

Specific actions to protect Scotts Valley polygonum include:

  • Protection through acquisition of or establishment of conservation easements on habitat in Scotts Valley,
  • Include conservation measures for Scotts Valley polygonum in Habitat Conservation Plan for the two listed insect species and the Ohlone tiger beetle with the City of Scotts Valley that minimizes loss of habitat from urban development, and
  • Conduct research focusing on habitat requirements for long-term survival of the species.2

Footnotes

1U.S. Fish and Wildlife Service. "Draft Recovery Plan for Two Insects (Polyphylla barbata and Trimerotropis infantilis) and Four Plants (Chorizanthe pungens var. hartwegiana, Chorizanthe robusta var. hartwegii, Erysimum teretifolium, and Polygonum hickmanii) from the Santa Cruz Mountains, California." Portland, Oregon: The Service, 1997, p. 31.

1U.S. Fish and Wildlife Service. "Recovery Plan for Insect and Plant Taxa from the Santa Cruz Mountains in California." Portland, Oregon: The Service, 1998, pp. 36-37.