Boechera ultraalsa
Snow mountain rockcress, Snow Mountain Rockcress
Family: Brassicaceae · Type: Perennial · Native
Conservation status: CNPS 1B.1
Boechera ultraalsa (Snow mountain rockcress) is a native California perennial in the Brassicaceae family, recognized by geographic isolation on Snow Mountain plus large seeds diagnostic.
Snow mountain rockcress is a rare (CNPS 1B.1) California native perennial found in the northern Coast Ranges, specifically around Snow Mountain in Lake County, growing in rocky soil at approximately 1,800 meters elevation. Flowering from June to July, this plant produces small white flowers on compact inflorescences with 3 to 4 blossoms. Growing with slender stems about 10 centimeters tall, it emerges from a woody caudex with distinctive long-stalked, 2 to 6-rayed hairs on its lower stem. Its basal leaves are entire, 4 to 6 millimeters wide, with long-stalked hairs that have 3 to 7 rays, while cauline leaves are sparse and become progressively hairier toward the stem's tip. The fruit is an erect-ascending silique 3 to 4 centimeters long, approximately 5 millimeters wide, and typically glabrous.
Identification and appearance
Key characters: 7 sympatric species; geographic isolation on Snow Mountain plus large seeds diagnostic
Habitat and range
Habitat: Rocky soil
Elevation: +- 1800 m.
Bloom period
Boechera ultraalsa blooms Jun-Jul.
Conservation status
CNPS 1B.1
How to tell it apart
vs Arabis: Boechera pods hang downward or curve and are wider (2mm+); Arabis pods stand rigidly erect and are narrower.; vs Matthiola: Boechera has flattened pods; Matthiola has cylindrical pods and densely hairy gray-green foliage.; vs Streptanthus: Boechera petals narrow gradually without a claw; Streptanthus petals have a distinct narrow claw at base.; vs Penstemon: Boechera has four-petaled flowers and seed pods; Penstemon has tubular five-lobed flowers.; vs Caulanthus: Boechera is perennial with a woody base; Caulanthus is typically annual or biennial without a woody caudex.
Frequently asked questions
Is Boechera ultraalsa native to California?
Yes. Boechera ultraalsa is native to California (recorded as native).
When does Boechera ultraalsa bloom?
Boechera ultraalsa blooms Jun-Jul.
What plant family does Boechera ultraalsa belong to?
Boechera ultraalsa is in the Brassicaceae family, genus Boechera.
Is Boechera ultraalsa rare or endangered?
Boechera ultraalsa carries California Rare Plant Rank 1B.1, state rank S1.
What habitat does Boechera ultraalsa grow in?
Boechera ultraalsa grows in Rocky soil.
Related species
Other California species in the same genus, family, or bioregion.
- Boechera xylopoda — Bigfoot hybrid rockcress
- Boechera yorkii — Last chance rockcress
- Boechera acutina — Pointed rockcress
- Boechera arcuata — Arching rockcress
- Boechera bodiensis — Bodie hills rockcress
- Boechera breweri — Brewer's rock cress
- Brassica fruticulosa — Mediterranean cabbage
- Brassica juncea — India mustard
Sources: Jepson eFlora · 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.