Taxon Report

Pentachaeta exilis (Gray) Gray ssp. aeolica Van Horn & Ornduff

San Benito pentachaeta

Print Report

Taxon Summary

Pentachaeta exilis ssp. aeolica, commonly known as San Benito pentachaeta, is a annual herb in the Asteraceae that is found only in California. It occurs within Cismontane woodland, and Valley and foothill grassland, growing at elevations from 480 to 855 meters. Pentachaeta exilis ssp. aeolica is ranked 1B.2, Plants Rare, Threatened or Endangered in California and Elsewhere; Moderately threatened in California.

Classification


Scientific Name:	Pentachaeta exilis (Gray) Gray ssp. aeolica Van Horn & Ornduff
Common Name:	San Benito pentachaeta
Family:	Asteraceae
Element Code:	PDAST6X041
USDA Plants Symbol:	PEEXA
Synonyms/Other Names:

Ecology and Life History


Lifeform:	annual herb
Blooming Period: Mar-May	Mar-May
Elevation:	480-855 (1575-2805)
General Habitats:	Cismontane woodland, Valley and foothill grassland
Microhabitat:
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	1B.2
Global Rank:	G5T2
State Rank:	S2
State List:	None
Fed List:	None
Other Status:	BLM_S; SB_SBBG; USFS_S
CRPR Changes:

Occurrence Data from the CNDDB


Total Occurrences:	16
Element Occurrence Ranks:
Excellent (A)	2
Good (B)	4
Fair (C)	0
Poor (D)	0
None (X)	0
Unknown (U)	10

Location


California Endemic: True
California Counties and Islands: Name (Code)
Monterey (MNT), San Benito (SBT), Santa Clara (SCL)
Quads: Name (Quad Code)
Alder Peak (3512183), Bear Canyon (3612113), Cone Peak (3612114), Eylar Mtn. (3712145), Hepsedam Peak (3612037), Isabel Valley (3712135), Jolon (3512182), Mt. Boardman (3712144), Mt. Stakes (3712134), San Benito Mtn. (3612036)

Threat List Data from the CNDDB


Threat List Total:	9
EOs with Threat Listed:	Total EOs	% of EOs
	5	31 %
Non-native plant impacts	4	25%
ORV activity	3	18%
Foot traffic/trampling	2	12%
Grazing	2	12%
Improper burning regime	1	6%
Feral pigs	1	6%
Other	1	6%
Recreational use (non-ORV)	1	6%
Road/trail construction/maint.	1	6%

Notes



Threatened by vehicles and grazing. Potentially threatened by foot traffic. Possibly threatened by non-native plants. See University of California Publications in Botany 65:1-41 (1973) for taxonomic 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 20 November 2025].