Taxon Report

Allium tribracteatum Torr.

three-bracted onion

Print Report

Taxon Summary

Allium tribracteatum, commonly known as three-bracted onion, is a perennial bulbiferous herb in the Alliaceae that is found only in California. It occurs within Chaparral, Lower montane coniferous forest, and Upper montane coniferous forest, growing at elevations from 1100 to 3000 meters. Allium tribracteatum is ranked 1B.2, Plants Rare, Threatened or Endangered in California and Elsewhere; Moderately threatened in California.

Classification


Scientific Name:	Allium tribracteatum Torr.
Common Name:	three-bracted onion
Family:	Alliaceae
Element Code:	PMLIL022D0
USDA Plants Symbol:	ALTR2
Synonyms/Other Names:

Ecology and Life History


Lifeform:	perennial bulbiferous herb
Blooming Period: Apr-Aug	Apr-Aug
Elevation:	1100-3000 (3610-9845)
General Habitats:	Chaparral, Lower montane coniferous forest, Upper montane coniferous forest
Microhabitat:	Volcanic
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	1B.2
Global Rank:	G2
State Rank:	S2
State List:	None
Fed List:	None
Other Status:	SB_SBBG; USFS_S
CRPR Changes:

Occurrence Data from the CNDDB


Total Occurrences:	38
Element Occurrence Ranks:
Excellent (A)	5
Good (B)	9
Fair (C)	2
Poor (D)	2
None (X)	0
Unknown (U)	20

Location


California Endemic: True
California Counties and Islands: Name (Code)
Alpine (ALP), Calaveras (CAL), El Dorado (ELD), Tuolumne (TUO)
Quads: Name (Quad Code)
Boards Crossing (3812032), Crandall Peak (3812022), Dardanelle (3811937), Devils Nose (3812044), Garnet Hill (3812043), Hull Creek (3812011), Kibbie Lake (3811917), Lake Eleanor (3711987), Liberty Hill (3812031), Mokelumne Peak (3812051), Pyramid Peak (3812072), Strawberry (3812021), Tamarack (3812041), Tiltill Mtn. (3811916), Tragedy Spring (3812062), Twain Harte (3812012)

Threat List Data from the CNDDB


Threat List Total:	11
EOs with Threat Listed:	Total EOs	% of EOs
	23	61 %
ORV activity	12	31%
Logging	11	28%
Other	7	18%
Road/trail construction/maint.	6	15%
Recreational use (non-ORV)	5	13%
Vandalism/dumping/litter	4	10%
Non-native plant impacts	3	7%
Foot traffic/trampling	2	5%
Grazing	2	5%
Wood cutting or brush clearing	1	2%
Development	1	2%

Notes



Threatened by vehicles. See Report of the Pacific Railroad Expedition 4:148 (1857) for original description, and Aliso 11(1):27-35 (1985) for revised treatment.
Threats:

Taxonomy:

Selected References

Citation California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 27 January 2025].