Lemmon’s milkvetch – State Wildlife Action Plan

Lemmon’s milkvetch is a perennial plant with numerous, widely branched and sparsely strigose prostrate stems that are loosely matted and 10-50 cm long. The leaves are 1-4.5 cm with 7-15 leaflets that are narrowly elliptic to oblanceolate, 2-11 by 1-2 mm, with obtuse to sub-acute tips. The leaf surface is abaxially strigillose and adaxially glabrate to glabrous. Leaf stipules are 2-5 mm and free. Inflorescences are subcapitate racemes with 2-13 flowers, peduncles 0.6-1.7 cm, bracts 0.8-2 mm, and pedicels 0.7-2.5 mm. Flowers are loosely ascending at anthesis with calyces 3-4 mm, strigillose and white sometimes with a few black hairs. The calyx tubes are 1.7-2.2 mm long with teeth subulate and 1.1-1.7 mm long. Corollas are whitish or tinged with lilac and 4.8-6.1 mm long, and banners are sometimes purple veined. Flowers have 4-8 ovules. Fruits are biocular and spreading or somewhat declined, elliptic or oblong-elliptic, compressed trigonous, straight, or somewhat incurved, ventrally carinate, 4-7 by 1.5-2.5 mm, strigillose, and with papery valves.

Overview

Species Common Name Lemmon's milkvetch
Species Scientific Name Astragalus lemmonii
Federal Listing Status Species of Concern
State Listing Status Threatened

Ecoregions

Northern Basin and Range

The Northern Basin and Range ecoregion covers the very large southeastern portion of the state, from Burns south to the Nevada border and from the Christmas Valley east to Idaho. It is largely a high elevation desert-like area dominated by sagebrush communities and habitats.

Special needs

Lemmon’s milkvetch forms colonies in moist, but often summer-dry, meadows and rushy flats along stream and lake shores. Grows in very deep, coarse textured soil.

Limiting factors

Threatened by grazing, development, human recreation, and non-native plants. Cattle grazing in a particular can cause soil compaction, introduction of invasive species, and damage Lemmon’s milkvetch from trampling. Altered site hydrology as a result of climate change and issues related to small population size are also threats.

Data gaps

Conduct pollinator studies. Develop seed germination, propagation, and transplanting protocols.

Conservation actions

Protect, maintain, and restore habitat. Limit disturbance, especially grazing, at known sites. Monitor existing populations. Collect and bank seed as insurance against local extirpation or extinction and to use in ex-situ research.

Key reference or plan

Marshall, DA, and J Brown. 2023. 2023 listing status assessment for Astragalus lemmonii (Lemmon’s milkvetch). Oregon Department of Agriculture, Salem, Oregon.