Eriogonum truncatum
Mount diablo buckwheat, Mount Diablo Buckwheat
(c) Arvel Hernandez, some rights reserved (CC BY) · licence
Family: Polygonaceae · Type: Herb · Native
Conservation status: CNPS 1B.1
Eriogonum truncatum (Mount diablo buckwheat) is a native California herb in the Polygonaceae family, recognized by Only 7 sympatric species; distinctive sessile involucres at branch tips.
Mount diablo buckwheat is a rare (CNPS 1B.1) California native annual found in the northern eastern San Francisco Bay and Sacramento Valley regions, specifically around Mount Diablo in Contra Costa County, growing in sandy habitats at elevations of 200 to 400 meters. Flowering from April to August, this plant produces delicate white to rose-colored flowers in small clustered inflorescences. Growing to 10 to 45 centimeters tall with tomentose (woolly) stems, it develops distinctive basal and cauline leaves 1 to 5 centimeters long with soft, hairy surfaces. Its leaves are relatively broad, measuring 1 to 2 centimeters wide, with a soft tomentose texture especially on the undersides. The small fruit, approximately 1.7 to 2 millimeters long, has a smooth tip and completes the plant's compact, intricate structure.
Identification and appearance
Key characters: Only 7 sympatric species; distinctive sessile involucres at branch tips
Habitat and range
Habitat: Sand
Elevation: 200-400 m
California counties: Contra Costa, Alameda
Bloom period
Eriogonum truncatum blooms Apr-Aug.
Conservation status
CNPS 1B.1
How to tell it apart
vs Adenostoma: Eriogonum has flowers in cup-like involucres; Adenostoma has tiny white rose-family flowers in spikes.; vs Salvia: Eriogonum has six similar perianth parts; Salvia has two-lipped tubular flowers.; vs Fagopyrum: Eriogonum has flowers in involucred clusters; Fagopyrum has loose branching sprays without involucres.; vs Artemisia: Eriogonum has cup-surrounded flower clusters; Artemisia has tiny inconspicuous heads in drooping sprays.; vs Chorizanthe: Eriogonum has multiple flowers per involucre; Chorizanthe has one flower per involucre with spiny teeth.
Frequently asked questions
Is Eriogonum truncatum native to California?
Yes. Eriogonum truncatum is native to California (recorded as native).
When does Eriogonum truncatum bloom?
Eriogonum truncatum blooms Apr-Aug.
Where in California does Eriogonum truncatum grow?
Eriogonum truncatum occurs in Contra Costa, Alameda, at elevations of 200-400 m.
What plant family does Eriogonum truncatum belong to?
Eriogonum truncatum is in the Polygonaceae family, genus Eriogonum.
Is Eriogonum truncatum rare or endangered?
Eriogonum truncatum carries California Rare Plant Rank 1B.1, state rank S1.
Related species
Other California species in the same genus, family, or bioregion.
- Eriogonum twisselmannii — Twisselmann's buckwheat
- Eriogonum umbellatum — Sulphur flower
- Eriogonum umbellatum var. ahartii — Ahart's buckwheat
- Eriogonum umbellatum var. argus — One-eyed sulphur flower
- Eriogonum umbellatum var. bahiiforme — Bay buckwheat
- Eriogonum umbellatum var. canifolium — Sherman pass sulphur flower
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.