Pediomelum megalanthum (Intermountain Indian breadroot)

Plate 1 figs. a–h · 3 observations

This species has been photographed under an open licence only 3 times, so some figures below are different views of the same plant, taken on the same day, rather than different individuals. They are usually different parts of it: the leaf, the flower, the bark.

Pediomelum megalanthum, photographed by Nolan Exe — fig. a Nolan Exe, CC BY 4.0 / 2021-05-01 / obs. 134122934

Pediomelum megalanthum, photographed by Matt Berger — fig. b Matt Berger, CC BY 4.0 / obs. 129049467

Pediomelum megalanthum, photographed by Alexandre Passos — fig. e Alexandre Passos, CC0 1.0 / obs. 188001872

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.

Native range 5 botanical countries

Native distribution of Pediomelum megalanthum, 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.

Region	TDWG code	Continent
Arizona	ARI	NORTHERN AMERICA
Colorado	COL
Nevada	NEV
New Mexico	NWM
Utah	UTA

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 127 observations

Condition	5th percentile	Median	95th percentile
Coldest month, mean daily low	-10.2 °C	-6.9 °C	0.0 °C
Warmest month, mean daily high	31.1 °C	32.5 °C	34.6 °C
Annual rainfall	227 mm	293 mm	535 mm
Rainfall in the driest quarter	25 mm	48 mm	67 mm

It is found where winters bring hard frost. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 127 research-grade observations of Pediomelum megalanthum 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 6 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.

Pediomelum epipsilum (Barneby) S.L.Welsh
Pediomelum retrorsum Rydb.
Psoralea epipsila Barneby
Psoralea megalantha Wooton & Standl.
Psoralea mephitica var. retrorsa (Rydb.) Kearney & Peebles
Psoralea retrorsa (Rydb.) Tidestr.

Sourcesevery claim on this page

World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.
Wikidata. common name (P1843), joined on the World Flora Online identifier (P7715). CC0. Retrieved 2026-07-13.
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.