CPC Plant Profile: Arrowleaf Thelypody
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Plant Profile

Arrowleaf Thelypody (Thelypodium eucosmum)

Thelyphodium eucosmum gets its common name from the arrow shaped leaves that clasp the stem. The flowers of this mustard are pinkish-purple. Photo Credit: Ed Florance
Description
  • Global Rank: G2 - Imperiled
  • Legal Status: N/A
  • Family: Brassicaceae
  • State: OR
  • Nature Serve ID: 154153
  • Date Inducted in National Collection: 02/10/1987

When in full bloom, the beautiful pink-purple flowered inflorescences and arrow-shaped leaves of Thelypodium eucosmum create spectacular show. These tall and spindly members of the mustard family stand out against the otherwise brown and gray sagebrush-covered hillsides of eastern Oregon. This plant is known only from two counties in eastern Oregon, and is found only within the lower canyons of the Blue Mountains and along the tributaries of the John Day River. There are many populations, but population levels are highly influenced by fluctuating stream levels and yearly rainfall amounts.

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Updates
  • 09/30/2020
  • Propagation Research

Germination trials conducted at The Berry Botanic Garden. Plants were subjected to constant 20C temperatures or alternating 20/10C temperatures both with and without an 8 week cold stratification period. Seeds not subjected to the cold stratification did not germinate. Of the seeds subjected to the 8 weeks of cold stratification, those in the constant 20C chamber had 50% germination while those in the alternating 20/10C had 71% germinate (BBG file).

  • 09/30/2020
  • Propagation Research

Germination trials conducted at Lewis and Clark College. Seeds were subjected to either a warm stratification 68F (20C) or a cold Stratification 41F (5C) for 6 weeks followed by either 59/41F (15C/5C) alternating temperatures or 68/50F (20C/10C) alternating temperatures. Seeds subjected to the warm stratification had very low germination (about 5%). Seeds subjected to 6 weeks of cold stratification germinated readily after being removed to the warmer germination chambers. Under alternating 59/41F (15C/5C) conditions, ~60% of the seeds germinated. Under alternating 68/50F (20C/10C) conditions, approximately 85% of the seeds germinated (Florance, pers. comm. 2001)

Nature Serve Biotics
  • 05/02/2017

Restricted to two counties in north-central Oregon. There are approximately 58 populations but many have less than 200 plants. Threats include grazing, flooding, irrigation projects, off-road vehicles, and mining.

Edward Guerrant, Ph.D.
  • 01/01/2010

Threats, as stated by Halvorson (Halvorson, pers. comm. 2001), include the following: Most historical sites were probably extirpated by livestock grazing. Consequently, most of the known populations are in areas not normally grazed by livestock, or gra

Edward Guerrant, Ph.D.
  • 01/01/2010

As of 2001: 55 populations on BLM land, 2 on National Forest land, and approx. 5 on private land. Populations range from 5 individuals to 5000, but vary greatly from year to year (ONHDB 2000).

Edward Guerrant, Ph.D.
  • 01/01/2010

Germination trials conducted at Lewis and Clark College. Seeds were subjected to either a warm stratification 68F (20C) or a cold Stratification 41F (5C) for 6 weeks followed by either 59/41F (15C/5C) alternating temperatures or 68/50F (20C/10C) alternating temperatures. Seeds subjected to the warm stratification had very low germination (about 5%). Seeds subjected to 6 weeks of cold stratification germinated readily after being removed to the warmer germination chambers. Under alternating 59/41F (15C/5C) conditions, ~60% of the seeds germinated. Under alternating 68/50F (20C/10C) conditions, approximately 85% of the seeds germinated (Florance, pers. comm. 2001) Germination trials conducted at The Berry Botanic Garden. Plants were subjected to constant 20C temperatures or alternating 20/10C temperatures both with and without an 8 week cold stratification period. Seeds not subjected to the cold stratification did not germinate. Of the seeds subjected to the 8 weeks of cold stratification, those in the constant 20C chamber had 50% germination while those in the alternating 20/10C had 71% germinate (BBG file).

Edward Guerrant, Ph.D.
  • 01/01/2010

50 of the 55 populations on BLM land are in active grazing allotments (Halvorson, pers. comm. 2001). One population was subjected to burning. Plants were robust the year after the fire, and two years of monitoring indicated that the population had fully recovered (Halvorson, pers. comm. 2001).

Edward Guerrant, Ph.D.
  • 01/01/2010

Study effect of disturbances on Thelypodium eucosmum (Halvorson, pers. comm. 2001). Study soil moisture relationships (Halvorson, pers. comm. 2001).

Edward Guerrant, Ph.D.
  • 01/01/2010

Collect and store seeds from across the range. Determine optimal germination conditions. Determine propagation and reintroduction protocols.

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Photos
Nomenclature
Taxon Thelypodium eucosmum
Authority B.L. Robins.
Family Brassicaceae
CPC Number 4274
ITIS 23395
USDA THEU
Common Names Arrow-leaf thelypody | world thelypody
Associated Scientific Names Thelypodium eucosmum
Distribution OROR: Lower canyons of the Blue Mountains in Grant Co. and Wheeler Co.
State Rank
State State Rank
Oregon S2
Habitat

Lower to intermediate elevations in the juniper-sagebrush series of plant communities (Meinke 1982). Steep basalt drainages which are wet for part of the year, streambanks in full sun or shade, vernally moist alkaline areas, hillside seeps, and under isolated western juniper trees away from obvious moisture (BLM 2002). Associated species include western juniper (Juniperus occidentalis), Great Basin wildrye (Elymus cinereus), big sagebrush (Artemisia tridentata), and rattlesnake brome (Bromus brizaeformis) (BLM 2002).

Ecological Relationships

Thelypodium eucosmum is often characterized as being a biennial or short-lived perennial, and may well often die after flowering once. Hitchcock et al. (1973) refer to it as a perennial that spreads by rootstocks, and note that individual clumps are usually mistaken to be taprooted biennial plants. At the Berry Botanic Garden, the plant behaves as a perennial that can flower for two or more years. The number of first year plants varies greatly each year depending on the amount of rainfall and other climactic conditions. However, the number of older plants appears to remain more stable despite weather conditions (Halvorson, pers. comm. 2001). Occasional episodes of significant natural disturbances often benefit the Arrow-leaf thelypody. Many seedlings have been observed in the bare soil created by a wind-thrown western juniper. While limited disturbances may encourage seedling growth, continued disturbances would most likely be detrimental to the population overall (Halvorson, pers. comm. 2001).

Pollinators
Common Name Name in Text Association Type Source InteractionID
Reintroduction
Lead Institution State Reintroduction Type Year of First Outplanting

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