Astragalus oophorus (Egg Milkvetch)

Plate 1 figs. a–h · 8 separate observations

Astragalus oophorus, photographed by Matt Berger — fig. a Matt Berger, CC BY 4.0 / 2021-05-18 / obs. 130485760

Astragalus oophorus, photographed by Rachel Lee Harper — fig. b Rachel Lee Harper, CC BY 4.0 / obs. 200792009

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 Astragalus oophorus, 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
California	CAL
Colorado	COL
Nevada	NEV
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 97 observations

Condition	5th percentile	Median	95th percentile
Coldest month, mean daily low	-14.3 °C	-9.5 °C	-5.1 °C
Warmest month, mean daily high	22.3 °C	27.4 °C	30.8 °C
Annual rainfall	137 mm	325 mm	521 mm
Rainfall in the driest quarter	14 mm	50 mm	80 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 97 research-grade observations of Astragalus oophorus 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 Reading one as the other would place a plant several zones too warm, so we do not publish a hardiness zone, because we do not have one.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 8 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.

Astragalus artipes A.Gray
Astragalus megacarpus var. caulescens M.E.Jones
Astragalus oophorus var. artipes (A.Gray) M.E.Jones
Astragalus oophorus var. typicus Barneby
Phaca artipes (A.Gray) Rydb.
Phaca jucunda Jeps. & Rydb.
Phaca oophora (S.Watson) Rydb.
Tragacantha oophora (S.Watson) Kuntze

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.