Arrow-leaf thelypody – State Wildlife Action Plan

Arrow-leaf thelypody is a biennial or short-lived perennial arising from a spreading rootstock. Plants are glabrous (except for leaf petioles) glaucous, and often purplish. Stems are 2-10 dm tall, branched distally, and either simple or branched near the base. Basal leaf petioles are (0.9-) 1.4-3 (-4.5) cm long and ciliate, the blades (2.8-) 3.5-8.8 (-11) cm long by (0.7-) 1-2.5 (-3.5) cm wide, usually oblong to oblanceolate or lanceolate, or rarely ovate or elliptic, acute at the apex, the margins entire to wavy. Cauline leaves are ascending and sessile, the blades 1.8-4.5 (-6) cm long by 0.5-1.6 (-2.4) cm wide, lanceolate to oblong, the base completely clasping to strongly auriculate, margins entire. Flowers are arranged in a lax to somewhat densely-flowered raceme, slightly elongated in fruit. Flower buds are purple and oblong-linear. Sepals are lilac-purple, erect, and linear-oblong, 5-7 (-8) mm long by (0.8-) 1-1.5 (-1.8) mm wide. Petals are dark purple, spatulate to oblanceolate, and attenuate at the base, (6.6-) 7.5-10 (-11.5) mm long by 1-1.8 (-2) mm wide. Anthers are purplish, well exserted, and coiled from the tip downward when fully dehisced. Siliques are narrowly linear, cylindrical, slightly constricted between the seeds, and straight to somewhat incurved, spreading to ascending, (2-) 2.4-5 (-6.5) cm long. Fruiting pedicels are straight or rarely curved, horizontal to spreading, (2.5-) 3-5.5 (-6.5) mm long, the gynophore (the elongated stalk bearing the pistil above the point of attachment of the calyx and corolla) (1-) 2.5-6 (-7.5) mm long in fruit.

Overview

Species Common Name Arrow-leaf thelypody
Species Scientific Name Thelypodium eucosmum
State Listing Status Threatened

Ecoregions

Blue Mountains

Located in NE Oregon, the Blue Mountains ecoregion is the largest ecoregion in the state. It provides a diverse complex of mountain ranges, valleys, and plateaus that extend beyond Oregon into the states of Idaho and Washington.

Special needs

Arrow-leaf thelypody occurs under or around western junipers (Juniperus occidentalis) along streambanks, canyons, seasonally-moist areas, seeps, and under isolated juniper trees away from obvious moisture. The species needs undisturbed, open but moist microsites.

Limiting factors

Arrow-leaf thelypody is endemic to lower canyons of the Blue Mountains and the tributaries of the John Day River. This species is palatable to cattle and sensitive to grazing pressure and trampling. Additional threats include flooding, invasive species, erosion, irrigation projects, off-road vehicles, and mining.

Data gaps

Conduct additional inventories to determine population size and distribution. Study soil moisture relationships. Determine germination and propagation requirements.

Conservation actions

Minimize or exclude grazing at priority sites. Collect and store seeds. Reduce impacts from weeds, focusing on high priority sites. Augment small populations with additional seed.

Key reference or plan

Meinke, R, K Amsberry, C Meinke, and R Currin. 2011. Population assessments and site observations for Thelypodium eucosmum in east-central Oregon: 2009 Field Season. Report prepared for BLM Prineville District Office. Report Prepared by Oregon Department of Agriculture, Salem, Oregon.