Thelypodium eucosmum

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Thelypodium eucosmum

Imperiled (NatureServe)
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Brassicales
Family: Brassicaceae
Genus: Thelypodium
Species: T. eucosmum
Binomial name
Thelypodium eucosmum

Thelypodium eucosmum is a species of flowering plant in the mustard family known by the common names arrow-leaf thelypody[1] and world thelypody. It is endemic to Oregon in the United States, where it is known from Grant and Wheeler Counties.[2] There are also historical records of the plant from Baker County.[3]

This species is a biennial or short-lived perennial herb. It produces an erect, branching stem which can reach a meter in height. The basal leaves are lance-shaped or sometimes oval in shape and are borne on a short petiole. The leaves higher on the stem are smaller and have no petiole.[4] They may clasp the stem[3] or may be arrowhead-shaped, with projections extending around the stem. The inflorescence is a raceme of many flowers with purple petals. The fruit is a silique up to 6.5 centimeters long.[4]

This species occurs in the Blue Mountains of Oregon, and along tributaries of the John Day River.[5] Its habitat is dominated by sagebrush and juniper. It grows in moist areas such as river canyons and streambanks.[2][5] The plant's population size is greatly affected by the availability of water.[5] Other plants in the habitat may include Balsamorhiza spp., Bromus mollis, B. tectorum, Ericameria nauseosa, Gutierrezia sarothrae, Hordeum murinum, Lepidium spp., Purshia tridentata, Salix spp., Sarcobatus vermiculatus, and Urtica dioica.[3]

Grazing is a main threat to the species; some populations have been extirpated by livestock grazing.[5]


  1. ^ "Thelypodium eucosmum". Natural Resources Conservation Service PLANTS Database. USDA. Retrieved 9 December 2015. 
  2. ^ a b Thelypodium eucosmum. Center for Plant Conservation.
  3. ^ a b c Thelypodium eucosmum. Oregon Department of Agriculture.
  4. ^ a b Thelypodium eucosmum. Flora of North America.
  5. ^ a b c d Thelypodium eucosmum. NatureServe.