Eriogonum umbellatum var. ahartii
Ahart's buckwheat
Photo: parent species Eriogonum umbellatum · Photo by Chez Brungraber
Family: Polygonaceae · Type: Shrub · Native
Conservation status: CNPS 1B.2
Eriogonum umbellatum var. ahartii (Ahart's buckwheat) is a native California shrub in the Polygonaceae family, recognized by serpentine habitat and rusty leaf undersides help distinguish from other varieties.
Ahart's buckwheat is a rare California native shrub ranked 1B.2 by CNPS, found in northern Sierra Nevada foothills near Paradise and Lumpkin ridges in Butte County, growing on serpentine landscapes at elevations of 400 to 1,000 meters. Flowering from June to September, this plant produces vibrant yellow flowers in compact umbellate clusters with delicate involucre tubes. Growing 3 to 8 decimeters tall with a spreading diameter of 5 to 13 decimeters, it has generally tomentose stems that create a distinctive woolly appearance. Its leaves are rusty-woolly underneath, measuring 1 to 2.5 centimeters long and 0.7 to 1.5 centimeters wide, with varying surface textures from hairy to glabrous. Its intricate inflorescence features main branches with multiple orders, creating a complex and textured botanical structure.
Identification and appearance
Key characters: 32 sympatric species; serpentine habitat and rusty leaf undersides help distinguish from other varieties
Habitat and range
Habitat: Serpentine
Elevation: 400-1000 m
California counties: Butte, Sierra, Yuba, Plumas
Bloom period
Eriogonum umbellatum var. ahartii blooms Jun-Sep.
Conservation status
CNPS 1B.2
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 umbellatum var. ahartii native to California?
Yes. Eriogonum umbellatum var. ahartii is native to California (recorded as native).
When does Eriogonum umbellatum var. ahartii bloom?
Eriogonum umbellatum var. ahartii blooms Jun-Sep.
Where in California does Eriogonum umbellatum var. ahartii grow?
Eriogonum umbellatum var. ahartii occurs in Butte, Sierra, Yuba, Plumas, at elevations of 400-1000 m.
What plant family does Eriogonum umbellatum var. ahartii belong to?
Eriogonum umbellatum var. ahartii is in the Polygonaceae family, genus Eriogonum.
Is Eriogonum umbellatum var. ahartii rare or endangered?
Eriogonum umbellatum var. ahartii carries California Rare Plant Rank 1B.2, state rank S3.
Related species
Other California species in the same genus, family, or bioregion.
- Eriogonum umbellatum var. argus — One-eyed sulphur flower
- Eriogonum umbellatum var. bahiiforme — Bay buckwheat
- Eriogonum umbellatum var. canifolium — Sherman pass sulphur flower
- Eriogonum umbellatum var. chlorothamnus — Sherwin grade sulphur flower
- Eriogonum umbellatum var. covillei — Coville's sulphur flower
- Eriogonum umbellatum var. dichrocephalum — Bicolor sulphur flower
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
Last updated 2026-09-30
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.