Taxon Report

Malacothamnus lucianus (Kearney) K. Morse

Arroyo Seco bushmallow

Print Report

Taxon Summary

Malacothamnus lucianus, commonly known as Arroyo Seco bushmallow, is a perennial deciduous shrub in the Malvaceae that is found only in California. It occurs within Chaparral, Cismontane woodland, and Meadows and seeps, growing at elevations from 5 to 915 meters. Malacothamnus lucianus is ranked 1B.2, Plants Rare, Threatened or Endangered in California and Elsewhere; Moderately threatened in California.

Classification


Scientific Name:	Malacothamnus lucianus (Kearney) K. Morse
Common Name:	Arroyo Seco bushmallow
Family:	Malvaceae
Element Code:	PDMAL0Q0B2
USDA Plants Symbol:
Synonyms/Other Names:	Malacothamnus palmeri (S. Watson) Greene var. lucianus Kearney

Ecology and Life History


Lifeform:	perennial deciduous shrub
Blooming Period: (Apr)May-Aug	(Apr)May-Aug
Elevation:	5-915 (15-3000)
General Habitats:	Chaparral, Cismontane woodland, Meadows and seeps
Microhabitat:
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	1B.2
Global Rank:	G1Q
State Rank:	S1
State List:	None
Fed List:	None
Other Status:	BLM_S; SB_CalBG/RSABG; SB_SBBG; USFS_S
CRPR Changes:

Occurrence Data from the CNDDB


Total Occurrences:	9
Element Occurrence Ranks:
Excellent (A)	0
Good (B)	3
Fair (C)	0
Poor (D)	2
None (X)	0
Unknown (U)	4

Location


California Endemic: True
California Counties and Islands: Name (Code)
Monterey (MNT)
Quads: Name (Quad Code)
Big Sur (3612137), Cone Peak (3612114), Junipero Serra Peak (3612124), Lopez Point (3612115), Partington Ridge (3612126)

Threat List Data from the CNDDB


Threat List Total:	6
EOs with Threat Listed:	Total EOs	% of EOs
	4	44 %
Altered flood/tidal/hydrologic regime	1	11%
Erosion/runoff	1	11%
Grazing	1	11%
Non-native plant impacts	1	11%
Other	1	11%
Road/trail construction/maint.	1	11%

Notes



See Leaflets of Western Botany 7(12):289-290 (1955) for original description.
Threats:
Threatened by road maintenance.
Taxonomy:
A synonym of M. palmeri in TJM (1993) and of M. palmeri var. palmeri in TJM 2; observations by field botanists suggest that recognition is warranted.

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 6 November 2025].