Ageratina shastensis
Shasta ageratina, Shasta ageratina, Shasta ageratina
(c) Matt Berger, some rights reserved (CC BY), uploaded by Matt Berger · licence
Family: Asteraceae · Type: Subshrub · Native
Conservation status: CNPS 1B.2
Ageratina shastensis (Shasta ageratina) is a native California subshrub in the Asteraceae family, recognized by differentiated by elevation range, leaf size, and inflorescence structure.
Shasta ageratina is a rare (CNPS 1B.2) California native perennial herb found in the Klamath Ranges on limestone or metavolcanic cliffs, in chaparral, and in conifer forest at elevations of 400 to 1,800 meters. Flowering from June to October, this plant produces white flowers in heads generally solitary or up to 3, approximately 1.2 centimeters long. Growing with erect or ascending glandular-hairy stems 13 to 45 centimeters tall, it has a woody caudex. Its proximal leaves are opposite while distal leaves are alternate, with blades 15 to 30 millimeters long, approximately deltate-ovate and serrate, somewhat hairy with glandular undersides. The fruit is 3 to 5.5 millimeters long.
Identification and appearance
Key characters: 1 sympatric species - differentiated by elevation range, leaf size, and inflorescence structure
Habitat and range
Habitat: Limestone or metavolcanic cliffs, chaparral, conifer forest
Elevation: 400-1800 m
Bloom period
Ageratina shastensis blooms Jun-Oct.
Conservation status
CNPS 1B.2
How to tell it apart
vs Baccharis: Ageratina has opposite leaves and bisexual flowers; Baccharis has alternate leaves and separate male/female plants.; vs Spiraea: Ageratina has composite flower heads; Spiraea has individual 5-petaled flowers in branched clusters.; vs Venegasia: Ageratina has white rayless flowers; Venegasia has large yellow ray petals and huge triangular leaves.; vs Eupatorium: Same genus (Eupatorium is old name); plants are identical.; vs Scrophularia: Ageratina has composite flower heads; Scrophularia has tubular two-lipped flowers typical of figworts.
Frequently asked questions
Is Ageratina shastensis native to California?
Yes. Ageratina shastensis is native to California (recorded as native).
When does Ageratina shastensis bloom?
Ageratina shastensis blooms Jun-Oct.
What plant family does Ageratina shastensis belong to?
Ageratina shastensis is in the Asteraceae family, genus Ageratina.
Is Ageratina shastensis rare or endangered?
Ageratina shastensis carries California Rare Plant Rank 1B.2, state rank S3.
What habitat does Ageratina shastensis grow in?
Ageratina shastensis grows in Limestone or metavolcanic cliffs, chaparral, conifer forest.
Related species
Other California species in the same genus, family, or bioregion.
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.