Taxon Report

Heuchera maxima Greene

island alumroot

Print Report


© 2014 Steve Matson

Taxon Summary

Heuchera maxima, commonly known as island alumroot, is a perennial rhizomatous herb in the Saxifragaceae that is found only in California. It occurs within Chaparral, Cismontane woodland, Coastal bluff scrub, and Coastal scrub, growing at elevations from 10 to 500 meters. Heuchera maxima is ranked 1B.2, Plants Rare, Threatened or Endangered in California and Elsewhere; Moderately threatened in California.

  Classification
Scientific Name:
 Heuchera maxima Greene
Common Name:
 island alumroot
Family: Saxifragaceae
Element Code: PDSAX0E0M0
USDA Plants Symbol: HEMA4
Synonyms/Other Names:

Ecology and Life History
Lifeform: perennial rhizomatous herb
Blooming Period: Feb-May Feb-May
Elevation: 10-500 (35-1640)
General Habitats: Chaparral, Cismontane woodland, Coastal bluff scrub, Coastal scrub
Microhabitat: Rocky
Microhabitat Details:

Conservation Status
CA Rare Plant Rank: 1B.2
Global Rank: G3
State Rank:
 S3
State List: None
Fed List: None
Other Status: SB_SBBG
CRPR Changes:

Occurrence Data from the CNDDB
Total Occurrences: 25
Element Occurrence Ranks:
   Excellent (A) 3
   Good (B) 5
   Fair (C) 2
   Poor (D) 0
   None (X) 0
   Unknown (U) 15

Location
California Endemic:  True
California Counties and Islands: Name (Code)
Santa Barbara (SBA), Ventura (VEN)
Quads: Name (Quad Code)
Anacapa Island (3311983), Santa Cruz Island A (3311987), Santa Cruz Island B (3311986), Santa Cruz Island C (3311985), Santa Cruz Island D (3311984), Santa Rosa Island East (3311988), Santa Rosa Island North (3312081)

Threat List Data from the CNDDB

Threat List Total: 1
EOs with Threat Listed: Total EOs % of EOs
1 4 %
Erosion/runoff 1 4%

Notes
Surveys in 1994-1996 have located many new populations. Threatened by feral herbivores on SCZ and SRO islands, and potentially threatened by seabird rookery on ANA Isl.
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 25 November 2025].