''Astragalus tweedyi'', or Tweedy's milkvetch, is a
perennial herb
In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal ...
in the
. It is native to
Washington and
Oregon in the
Pacific Northwest of the United States.
Taxonomy
''Astragalus tweedyi'' was described and published in 1890 by
William Marriott Canby
William Marriott Canby Sr. (1831–1904) was an American banker, business executive, philanthropist and botanist. He is famous as a leading expert on the flora of Delaware and the "eastern shore" region of Maryland and as an epistolary corresponde ...
, who named it in honor of
Frank Tweedy, one of the first to collect it, in the hills along the
Columbia River
The Columbia River (Upper Chinook: ' or '; Sahaptin: ''Nch’i-Wàna'' or ''Nchi wana''; Sinixt dialect'' '') is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, C ...
in
Yakima County, Washington Territory in 1883. At the time, he was working as a topographer on the Northern Transcontinental Survey. Canby was head of Economic Botany for the project.
It had been collected by
Thomas J. Howell who called it ''
Astragalus collinus''. Canby agreed it was closely allied to ''collinus'', but easily distinguished based on leaves and pods, justifying creation of a new species.
[Canby, W.M. 1890. ''Astragalus Tweedyi'' n. sp. in Some Western Plants. Bot. Gaz. 15: 150]
Univ Chicago Press Journals
/ref>[''Astragalus'' in Hitchcock, C.L., and Cronquist, A. 1973. Flora of the Pacific Northwest. U. Washington Press.] Tweedy's specimen, the isolectotype
In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes the ...
, is deposited in Gray Herbarium
The Harvard University Herbaria and Botanical Museum are institutions located on the grounds of Harvard University at 22 Divinity Avenue, Cambridge, Massachusetts. The Botanical Museum is one of three which comprise the Harvard Museum of Natural ...
at Harvard.[''Astragalus Tweedyi'' type (in part), Gray Herbarium](_blank)
/ref>
Description
''Astragalus tweedyi'' is a much-branched sparsely hairy perennial herb to high. Leaves are long, and pinnately
Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, and in ...
-compound with 15-21 narrow leaflets. The flowers are typical pea flowers, with five petals: banner, two wings and a keel. They are creamy in color and ascending on the rachis. The pods are erect at maturity, to long, and circular in cross-section.
Distribution and habitat
''Astragalus tweedyi'' is endemic to south central Washington and north central Oregon. It grows on dry, somewhat rocky, hillsides and meadows, from , mostly in a sagebrush-bunchgrass
Tussock grasses or bunch grasses are a group of grass species in the family Poaceae. They usually grow as singular plants in clumps, tufts, hummocks, or bunches, rather than forming a sod or lawn, in meadows, grasslands, and prairies. As perennial ...
association.
Conservation status
''Astragalus tweedyi'' was a candidate species for listing under the United States Endangered Species Act of 1973. It was removed in 1985 because it is more abundant and widespread, and less threatened than previously believed.Federal Register: 50 Fed. Reg. 39073 (Sept. 27, 1985).
/ref>
References
{{taxonbar, from=Q15524768
tweedyi
Perennial plants
Plants described in 1890
Columbia River
Yakima County, Washington
Taxa named by William Marriott Canby