Castilleja rhexiifoliaRydb.

splitleaf Indian paintbrush

WFO wfo-1000059118 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h · 8 separate observations

Castilleja rhexiifolia, photographed by Julia Carr
fig. a Julia Carr, CC0 1.0 / 2021-08-16 / obs. 157785186
Castilleja rhexiifolia, photographed by J Straka
fig. b J Straka, CC BY 4.0 / obs. 171196566
Castilleja rhexiifolia, photographed by J Straka
fig. c J Straka, CC BY 4.0 / obs. 171201755
Castilleja rhexiifolia, photographed by Melissa McMasters
fig. d Melissa McMasters, CC BY 4.0 / obs. 153217853
Castilleja rhexiifolia, photographed by Reid Hardin
fig. e Reid Hardin, CC BY 4.0 / obs. 144564925
Castilleja rhexiifolia, photographed by Reid Hardin
fig. f Reid Hardin, CC BY 4.0 / obs. 144570420
Castilleja rhexiifolia, photographed by Spencer Quayle
fig. g Spencer Quayle, CC0 1.0 / obs. 141066975
Castilleja rhexiifolia, photographed by Mike Duran
fig. h Mike Duran, CC BY 4.0 / obs. 143224280

Every figure is a research-grade observation under CC0, CC BY or CC BY-SA, rehosted with the photographer’s name, the licence and the observation it came from. Photographs under a NonCommercial licence are excluded from this site and are never stored, which costs us a great many pictures and is not negotiable.

The specimen a real sheet, in a real collection

Herbarium
The New York Botanical Garden
Accession
68160
Filed as
Castilleja rhexiifolia var. pubens A.Nelson & J.F.Macbr.
Det. by
not recorded on this sheet
Collected
A. Nelson 1912-07-11
Origin
US
The sheet
View the digitised specimen (CC BY 4.0)

A real pressed plant, in a real collection, under the accession number above. Not an illustration of one. The holding institution does not serve this sheet’s image to third parties, so there is no photograph here. The record is real and the link goes to it. Where we hold no openly licensed sheet for a species this section is simply absent, and where a sheet never recorded who determined it, that field stays empty rather than being filled in. Roughly half of all herbarium sheets never recorded a determiner, which is ordinary.

Native range 10 botanical countries

Regions where Castilleja rhexiifolia is native: Alberta, British Columbia, Colorado, Idaho, Montana, New Mexico, Oregon, Utah, Washington, Wyoming AlbertaBritish ColumbiaColoradoIdahoMontanaNew MexicoOregonUtahWashingtonWyoming
Native distribution of Castilleja rhexiifolia, after Kew’s World Checklist of Vascular Plants. Introduced, extinct and doubtful records are excluded, so this is where the plant is from, not everywhere it now grows.
RegionTDWG codeContinent
Alberta ABT NORTHERN AMERICA
British Columbia BRC
Colorado COL
Idaho IDA
Montana MNT
New Mexico NWM
Oregon ORE
Utah UTA
Washington WAS
Wyoming WYO

Region boundaries approximated from Natural Earth (public domain) and mapped to TDWG World Geographical Scheme for Recording Plant Distributions (WGSRPD) level-3 botanical countries (Brummitt 2001). Indicative, not the official WGSRPD geometry.

Where it actually grows measured, from 1,991 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -20.8 °C -17.5 °C -12.7 °C
Warmest month, mean daily high 15.2 °C 18.9 °C 24.2 °C
Annual rainfall 708 mm 1,013 mm 1,495 mm
Rainfall in the driest quarter 107 mm 178 mm 294 mm

It is found where winters are severely cold. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 1,991 research-grade observations of Castilleja rhexiifolia that carry a coordinate, and this is the range those places actually span. The 5th and 95th percentiles are used rather than the minimum and maximum, because a single cultivated specimen in a heated conservatory should not widen a tropical plant's range to the Arctic.

This is not a hardiness zone. A USDA zone is the average annual extreme minimum temperature. The figure above is the mean daily minimum of the coldest month, which is a different quantity and is typically far warmer. Reading one as the other would place a plant several zones too warm, so we do not publish a hardiness zone, because we do not have one.

Also published as 9 synonyms

A synonym is not an error. It is a record of botanists disagreeing, in print, about where this plant belongs. Each of these was somebody’s considered answer.

  • Castilleja humilis Rydb.
  • Castilleja lanceifolia Rydb.
  • Castilleja lauta A.Nelson
  • Castilleja leonardii Rydb.
  • Castilleja magna Rydb.
  • Castilleja obtusiloba Rydb.
  • Castilleja oregonensis Gand.
  • Castilleja purpurascens Rydb.
  • Castilleja subpurpurascens Rydb.

Sourcesevery claim on this page

  1. World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
  2. iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.
  3. USDA PLANTS Database. common name, checklist symbol CARH4. public domain. Retrieved 2026-07-13.
  4. Kew, World Checklist of Vascular Plants (WCVP v16). native distribution by TDWG level-3 botanical country, and life form. CC BY 3.0. Retrieved 2026-06-04.

We publish what we can source and we say so when we cannot. This page has no care advice and no toxicity claim, because we do not yet have those from a source we can cite.