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Howell's Spectacular Thelypody

Thelypodium howellii ssp. spectabilis

Status Threatened
Listed May 26, 1999
Family Cruciferae (Brassicaceae)
Description Basal leaves have wavy edges and are arranged in a rosette. Flowers appear in loose spikes at the ends of the stems and have four purple petals. Has fruits that are long, slender pods.
Habitat Wet alkaline meadows in valley bottoms, usually in and around woody shrubs.
Threats Urban and agricultural development.
Range Oregon

Description

Howell's spectacular thelypody, Thelypodium howellii ssp. spectabilis grows to approximately 2 ft (0.6 m) tall, with branches arising from near the base of the stem. The basal leaves are approximately 2 in (5 cm) long with wavy edges and are arranged in a rosette. Stem leaves are shorter, narrow, and have smooth edges. Flowers appear in loose spikes at the ends of the stems. Flowers have four purple petals approximately 0.75 in (2 cm) in length, each of which is borne on a short 0.25 in (0.6 cm) stalk. Fruits are long, slender pods. This taxon is distinguished from T. howellii ssp. howellii by its larger petals and the paired filaments that are not united.

Habitat

Howell's spectacular thelypody occurs in wet alkaline meadows in valley bottoms, usually in and around woody shrubs that dominate the habitat on the knolls and along the edge of the wet meadow habitat between the knolls. Associated species include greasewood, alkali saltgrass, giant wild rye, alkali cordgrass, and alkali bluegrass. Soils are pluvial-deposited alkaline clays mixed with recent alluvial silts, and are moderately well-drained.

Due to its relatively low elevation and rich soils, agriculture is the primary land use in the Baker-Powder River Valley region, which contains the 11 extant Howell's spectacular thelypody sites. The region is bordered on the west by the Elkhorn Mountains and on the east by the Wallowa Mountains. Annual precipitation for the Baker Valley averages 10.6 in (27 cm), most falling as snow in winter. Weather patterns follow the interior continental weather systems with little maritime influence. Winters are cold, and summers are warm and dry.

Distribution

The plant is currently known from 11 sites (five populations) ranging in size from 0.03 acres (121.4 sq m) to 41.4 acres (16.8 hectares) in the Baker-Powder River valley in Baker and Union counties. The total occupied habitat for this species is approximately 100 acres (40.5 hectares). Plants at the type locality in Malheur County have not been relocated since 1927 and are considered to be extirpated. The entire extant range of this taxon lies within a 13-mi (21-km) radius of Haines, Oregon.

This species was thought to be extinct until re-discovered in 1980 near North Powder. The 11 recently discovered sites containing Howell's spectacular thelypody are located near the communities of North Powder, Haines, and Baker. The North Powder Howell's spectacular thelypody population contains five sites; the largest is measures approximately 41.4 acres (16.8 hectares). Until recently, one site near the town of North Powder, less than 2.3 acres (0.9 hectares) in size, had a plant protection agreement between the landowner and the Nature Conservancy. The Haines plant population currently consists of three small sites located in or near the town of Haines. In 1998 an additional site in Haines was identified and one previously known site in Haines was apparently extirpated by development. A 1.8-acre (0.7-hectare) site west of Baker is within a 20-acre (8.l-hectare) pasture adjacent to a road. Another site north of Baker (0.08 acres; 323.8 sq m) exists in a small remnant of meadow habitat surrounded by farmland. One site approximately 5 mi (8 km) north of North Powder is located on private land at Clover Creek.

Threats

Most of the habitat for Howell's spectacular thelypody has been modified or lost to urban and agricultural development. Habitat degradation at all remaining sites for this species is due to a combination of livestock grazing, agricultural conversion, hydrological modifications, and competition from non-native vegetation. These activities have resulted in the extirpation of Howell's spectacular thelypody from about half its former range in Baker, Union, and Malheur counties. Plants at the type locality in Malheur County are considered to be extirpated due to past agricultural development. Since 1990, at least 40% of the sites sampled in North Powder that previously contained Howell's spectacular thelypody have been extirpated. These sites were all located within areas subjected to grazing. Grazing, trampling, exotic species, and agricultural activities continue to threaten virtually all remaining habitat for this species.

Within the City of Haines, all remaining habitat containing Howell's spectacular thelypody is being impacted by residential construction, trampling, and other activities. In 1994, a large section of habitat formerly occupied by Howell's spectacular thelypody at the Haines rodeo grounds was destroyed when a parking lot was constructed. Although an estimated 5000-10,000 Howell's spectacular thelypody plants were present at the Haines rodeo grounds in late June 1998, the majority of this population was subsequently impacted by the July 4 and 5 rodeo; the site was apparently mowed and used as a parking area during the rodeo. Immediately after the rodeo, fewer than 300 Howell's spectacular thelypody plants were observed at the site. Most of these plants were found along the fence line adjacent to the main road outside the rodeo grounds. It is possible that the Howell's spectacular thelypody population may recover from this disturbance. However, it is unlikely that the entire population was able to reproduce successfully prior to mowing since most plants were in full bloom (without mature fruits in late June.

Howell's spectacular thelypody habitat within a proposed racing area development project adjacent to the rodeo grounds, will likely be impacted by the proposed project. However, since no specific Howell's spectacular thelypody surveys have been completed for this project, it is unclear how many Howell's spectacular thelypody plants will be affected.

Livestock grazing can negatively affect habitat and contribute to reduced reproduction of this species. In particular, spring and early summer grazing adversely affects reproduction for Howell's spectacular thelypody by removing flowers and/or fruits, and individual plants get trampled during the period of active growth (generally from May through July).

In July 1995, cattle consumed all Howell's spectacular thelypody plants that were present within a pasture at Clover Creek; plants were only observed in an adjacent area that was not subject to grazing. The Clover Creek site (39.2 acres; 16 hectares) supports the second largest remaining plant habitat area.

At another site intentionally not grazed for the last five years, Howell's spectacular thelypody plants have expanded into areas previously unoccupied. Areas that were previously heavily grazed now contain higher densities and larger plants than marginal refugia habitat beneath Sarcobatus. However, this site, while under a permanent conservation easement, has been subjected to trespass grazing on at least two occasions during the past three years.

Conservation and Recovery

One population of Howell's spectacular thelypody occurs on a permanent conservation easement on private land near North Powder, Oregon that may be managed for the long-term protection of this species.

The U. S. Fish and Wildlife Service (FWS) is working with willing landowners and State, local, and Federal agencies to ensure that grazing and other activities are managed to reduce impacts to this species and its habitat. In addition, the State and local weed management agencies have initiated measures that afford some protection to Howell's spectacular thelypody, such as identifying areas to be avoided by herbicide application, and placing signs in the area.

The livestock grazing threat is being addressed by working directly with landowners to adjust seasonal use and through fence construction to limit livestock trespass. The plant is palatable to livestock, and grazing occurring from April through July can be detrimental to annual seed production; grazing at other times of the year has little direct effect. Altered grazing practices can only be achieved through voluntary efforts of landowners; designation of critical habitat would not change grazing practices.

Contacts

U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N.E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
http://pacific.fws.gov/

U.S. Fish and Wildlife Service
Snake River Basin Office
1387 S. Vinnell Way, Room 368
Boise, Idaho 83709
Telephone: (208) 378-5243
Fax: (208) 378-5262

References

Antell, K.S. 1990. "Howell's thelypody: a rare biennial mustard from Oregon." Biology Department, Eastern Oregon State College, LaGrande, Oregon.

Davis, J.S. and B. Youtie. 1995. "Site information and analysis: North Powder Thelypodium howellii ssp. spectabilis preserve." Prepared for The Nature Conservancy, Oregon Field Office, Portland, Oregon.

Kagan, J.S. 1986. "Status report for Thelypodium howellii ssp. spectabilis." Oregon Natural Heritage Data Base, Portland, Oregon.

Oregon Department of Fish and Wildlife (ODFW). 1996. "Miles wetlands five-year action plan: 1997-2002." Prepared for the U.S. Fish and Wildlife Service.

Oregon Natural Heritage Program. 1998. "Element occurrence records for Thelypodium howellii ssp. spectabilis."

U. S. Fish and Wildlife Service. 26 May 1999. "Threatened Status for the Plant Thelypodium howellii ssp. spectabilis (Howell's spectacular thelypody)." Federal Register 64(101):28393-28403.

Whitson, T.D., et. al. 1996. Weeds of the West, 5th edition. University of Wyoming and the Western Society of Weed Science, Newark, California.

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Howell's Spectacular Thelypody

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