Bitterbrush Antelope Brush Antelope Bitterbrush
Purshia tridentata
Rosaceae · broadleaf deciduous shrub · introduced
Last updated
Purshia tridentata (Rosaceae) is a deciduous to semi-evergreen shrub native to the dry interior of western North America from British Columbia to Baja California and east to Montana and New Mexico. It grows 3 to 8 feet tall with a rounded habit and small, three-lobed (tridentate) leaves. Small, fragrant, creamy yellow flowers appear in late spring.
Bitterbrush is a critical browse plant for mule deer and other wildlife in sagebrush-steppe ecosystems. It grows in full sun on dry, well-drained soils and is extremely drought tolerant. The species fixes atmospheric nitrogen. It is rarely used in ornamental plantings but has significant value for habitat restoration in arid rangelands.
Quick Facts
Phenological Calendar
As of May 24, 2026, Puget Sound stations range from 2172.5 to 2394 GDD₃₂. Bitterbrush Antelope Brush Antelope Bitterbrush has passed 'first bloom' (1214 GDD₃₂).
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of May 24, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,394 | 'First bloom' | — | — |
| Kent / Auburn | 2,373 | 'First bloom' | — | — |
| Seattle / UW | 2,332 | 'First bloom' | — | — |
| Olympia / Tumwater | 2,295 | 'First bloom' | — | — |
| Tacoma / Puyallup | 2,259 | 'First bloom' | — | — |
| Bellingham / Whatcom | 2,256 | 'First bloom' | — | — |
| Sequim / Rain Shadow | 2,173 | 'First bloom' | — | — |
View full calendar (2 stages)
| Stage | GDD32 | Typical Window |
|---|---|---|
| 'Flower buds visible' BBCH '51' | 1021 | '' |
| ● 'First bloom' BBCH '61' NOW | 1214 | '' |
Source: 'NPN citizen science observations (WA+OR), n=12, median. services.usanpn.org' About GDD₃₂ →
Season tracker for Kent / Auburn as of May 24, 2026. Predicted dates use 16-day weather forecast through Jun 9, 2026, then climate normals.