Tall western penstemon – State Wildlife Action Plan

Tall western penstemon is perennial forb typical of the genus in that it has opposite leaves, flower clusters born in axils of upper bracts, and tubular flowers (of five fused petals) with four fertile, pollenproducing anthers and a fifth sterile anther modified into a staminode. Stems and axes of the inflorescence are glabrous to pubescent, or rarely retrorsely hairy, but not pubescent, with main stems generally 50-80 cm tall, but as tall as over 1 meter. Basal and cauline leaves are glabrous and not leathery, with an entire margin, about 3-7 cm long and 1.0-1.5 cm wide, with an oblanceolate to elliptic leaf blade, entire margins, tapered base and obtuse to acute tip that is rarely mucronate. lnfloresences are compact panicles with the main axis obscured by cymose subaxes (thyrses), typically 3-10 cm long, with two cymes of 5-11 flowers at each node. The showy flowers are violet to blue or purple, funnelform and 10-14 mm long, lower lip yellow-bearded, and variable calyx lobes 4-9 mm long. Fruits are glabrous capsules, 4-5 x 3-4 mm, produced mid- to late summer.

Overview

Species Common Name Tall western penstemon
Species Scientific Name Penstemon hesperius
Federal Listing Status Species of Concern
State Listing Status Endangered

Ecoregions

Willamette Valley

The Willamette Valley ecoregion is bounded on the west by the Coast Range and on the east by the Cascade Range. This long mostly level alluvial plain has some scattered areas of low basalt, and contrasts with productive farmland and large urban areas. It has the fastest-growing human population in the state resulting in challenges due to land-use changes.

Special needs

Tall western penstemon occurs in meadow and riparian habitats in the upper Willamette Valley.

Limiting factors

Habitat is limited. The species is very threatened by urban and suburban development and habitat conversion to agriculture. Tall western penstemon is also threatened by invasive plants in riparian habitat.

Data gaps

Assess pollinator activity and reproductive success of known populations. Assess climate change vulnerability. Document population status and trends.

Conservation actions

Protect, maintain, and restore habitat. Limit disturbance at known sites. Monitor existing populations. Identify suitable habitat on public land for introductions within the historic range of the species.

Key reference or plan

Marshall, DA. 2024. 2024 listing status assessment for Penstemon hesperius (tall western penstemon). Oregon Department of Agriculture, Salem, Oregon.