Taxon Report

Thamnolia vermicularis (Swartz) Ach. ex Schaerer

whiteworm lichen

Print Report

Taxon Summary

Thamnolia vermicularis, commonly known as whiteworm lichen, is a fruticose lichen (terricolous) in the Icmadophilaceae that is found in California and elsewhere. It occurs within Chaparral, and Valley and foothill grassland, growing at elevations from 90 to 90 meters. Thamnolia vermicularis is ranked 2B.1, Plants Rare, Threatened, or Endangered in California, But More Common Elsewhere; Seriously threatened in California.

Classification


Scientific Name:	Thamnolia vermicularis (Swartz) Ach. ex Schaerer
Common Name:	whiteworm lichen
Family:	Icmadophilaceae
Element Code:	NLTES43860
USDA Plants Symbol:	THVE60
Synonyms/Other Names:

Ecology and Life History


Lifeform:	fruticose lichen (terricolous)
Blooming Period:
Elevation:	90-90 (295-295)
General Habitats:	Chaparral, Valley and foothill grassland
Microhabitat:	Rocky, Sandstone
Microhabitat Details:	On rocks derived from sandstone

Conservation Status


CA Rare Plant Rank:	2B.1
Global Rank:	G5
State Rank:	S1
State List:	None
Fed List:	None
Other Status:
CRPR Changes:	added to 2B.1 on 2014-03-01

Occurrence Data from the CNDDB


Total Occurrences:	1
Element Occurrence Ranks:
Excellent (A)	0
Good (B)	0
Fair (C)	0
Poor (D)	0
None (X)	0
Unknown (U)	1

Location


California Endemic: False
California Counties and Islands: Name (Code)
Marin (MRN)
Quads: Name (Quad Code)
Tomales (3812228), Valley Ford (3812238)

Threat List Data from the CNDDB


Threat List Total:	4
EOs with Threat Listed:	Total EOs	% of EOs
	1	100 %
Agriculture	1	100%
Development	1	100%
Foot traffic/trampling	1	100%
Road/trail construction/maint.	1	100%

Notes



Known in CA only from near Dillon Beach. Preferred habitat may exist on Mt. Shasta; needs field surveys. Possibly threatened by trampling and foot traffic. See Bulletin of the California Lichen Society 16(2):21-26 (2009) for CALS Conservation Committee sponsorship.
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 16 November 2025].