Taxon Report

Ivesia paniculata T.W. Nelson & J.P. Nelson

Ash Creek ivesia

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Taxon Summary

Ivesia paniculata, commonly known as Ash Creek ivesia, is a perennial herb in the Rosaceae that is found only in California. It occurs within Great Basin scrub, Pinyon and juniper woodland, and Upper montane coniferous forest, growing at elevations from 1500 to 1950 meters. Ivesia paniculata is ranked 1B.2, Plants Rare, Threatened or Endangered in California and Elsewhere; Moderately threatened in California.

Classification


Scientific Name:	Ivesia paniculata T.W. Nelson & J.P. Nelson
Common Name:	Ash Creek ivesia
Family:	Rosaceae
Element Code:	PDROS0X0S0
USDA Plants Symbol:	IVPA
Synonyms/Other Names:

Ecology and Life History


Lifeform:	perennial herb
Blooming Period: May-Aug	May-Aug
Elevation:	1500-1950 (4920-6400)
General Habitats:	Great Basin scrub, Pinyon and juniper woodland, Upper montane coniferous forest
Microhabitat:	Gravelly (sometimes), Rocky (sometimes), 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:	BLM_S; SB_UCSC; USFS_S
CRPR Changes:

Occurrence Data from the CNDDB


Total Occurrences:	26
Element Occurrence Ranks:
Excellent (A)	6
Good (B)	12
Fair (C)	0
Poor (D)	0
None (X)	1
Unknown (U)	7

Location


California Endemic: True
California Counties and Islands: Name (Code)
Lassen (LAS), Modoc (MOD)
Quads: Name (Quad Code)
Ambrose Valley (4112027), Ash Valley (4112016), Lane Reservoir (4112017), Letterbox Hill (4112018), Said Valley (4012087), Whitinger Mtn. (4012086)

Threat List Data from the CNDDB


Threat List Total:	7
EOs with Threat Listed:	Total EOs	% of EOs
	22	85 %
Grazing	18	69%
Road/trail construction/maint.	8	30%
Logging	5	19%
Foot traffic/trampling	5	19%
ORV activity	4	15%
Wood cutting or brush clearing	2	7%
Mining	1	3%

Notes



Known only from the Ash Valley region. Protected in part at Ash Valley RNA (BLM).
Threats:
Threatened by road maintenance, logging, trampling, and grazing.
Taxonomy:
Previously included as I. corymbosa, a name that was never validly published.

Selected References

Brittonia 33(2):165-167 (1981)

Ivesia paniculata profile for potential Species of Conservation Concern evaluation (2018)

Fremontia 16(1):15-17 (1988) [BLM management plans]

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 October 2025].