Howell's spectacular thelypody was federally listed as threatened without critical habitat in 1999 (U.S. Fish and Wildlife Service 1999). A draft recovery plan is available for review (U.S. Fish and Wildlife Service 2001).

Description and Life History

Howell's spectacular thelypody is a biennial plant in the mustard family (Brassicaceae). It grows to approximately 60 cm (24 in) tall, with branches arising from near the base and arrowhead-shaped leaves. The sepals are green, purple or lavender in color, and the 4-petaled flowers are lavender to purple. Flowering typically occurs from June through July. The petal shape and paired free filaments distinguish T. howellii ssp. spectabilis from T. howellii ssp. howellii.

Habitat

Howell's spectacular thelypody occurs in moist, moderately well-drained, somewhat alkaline meadow habitats, typically growing with salt tolerant species such as greasewood (Sarcobatus vermiculatus), giant wild rye (Elymus cinereus), and goosefoot (Chenopodium spp.). Howell's spectacular thelypody appears to be dependent on periodic flooding because it rapidly colonizes areas adjacent to streams that have flooded. The species occurs on soils in the Wingville, Baldock and Haines Series (NRCS mapped soil unit STATSGO 179).

Reasons for Decline

The plant has been extirpated from about one-third of known historic sites, including the type locality in Malheur county. Threats to the taxon include 1) habitat loss due to urban and agricultural development; 2) habitat degradation due to livestock grazing and hydrological modification; 3) consumption by livestock; 4) use of herbicides or mowing during the growing season; and 5) competition with exotic species such as teasel (Dipsacus sylvestris), bull thistle (Cirsium vulgare), Canada thistle (C. canadensis), and yellow sweet clover (Melilotus officinalis).

Range

This species occurs at 18 sites in the Baker-Powder River Valley located in Union and Baker Counties, Oregon.

References and Links

U.S. Fish and Wildlife Service. 1999. Threatened Status for the Plant Thelypodium howellii ssp. spectabilis (Howell's spectacular thelypody). Federal Register 64:28393-28403. http://frwebgate.access.gpo.gov/cgi-bin/getdoc.cgi?dbname=1999_register&docid=fr26my99-16.pdf

U.S. Fish and Wildlife Service. 2002. Notice of Availability of a Final Recovery Plan for the Howell's Spectacular Thelypody (Thelypodium howellii ssp. spectabilis). Federal Register 67:50626-50627. http://frwebgate.access.gpo.gov/cgi-bin/getdoc.cgi?dbname=2002_register&docid=fr05au02-17.pdf

U.S. Fish and Wildlife Service. 2002. Recovery Plan for Howell's Spectacular Thelypody. http://ecos.fws.gov/docs/recovery_plans/2002/020603.pdf