Erythronium rostratumW.Wolf

Yellow fawn lilyyellow troutlily

WFO wfo-0000766972 Accepted WFO 2026-06 8 photographs CC0 / CC BY / CC BY-SA

Plate 1 figs. a–h · 8 separate observations

Erythronium rostratum, photographed by Christopher Zacharias
fig. a Christopher Zacharias, CC BY 4.0 / 2022-04-02 / obs. 185913411

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
3534313
Filed as
Erythronium rostratum W.Wolf
Det. by
not recorded on this sheet
Collected
R. M. Harper 1940-03-23
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 11 botanical countries

Regions where Erythronium rostratum is native: Alabama, Arkansas, Kansas, Kentucky, Louisiana, Mississippi, Missouri, Ohio, Oklahoma, Tennessee, Texas AlabamaArkansasKansasKentuckyLouisianaMississippiMissouriOhioOklahomaTennesseeTexas
Native distribution of Erythronium rostratum, 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
Alabama ALA NORTHERN AMERICA
Arkansas ARK
Kansas KAN
Kentucky KTY
Louisiana LOU
Mississippi MSI
Missouri MSO
Ohio OHI
Oklahoma OKL
Tennessee TEN
Texas TEX

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.

Flowering 181 in flower of 234 examined

Proportion of examined Erythronium rostratum in flower, by month
Month In flower Examined Share 95% interval
Jan 0 0 too few examined
Feb 11 12 92% 65% to 99%
Mar 137 170 81% 74% to 86%
Apr 33 52 63% 50% to 75%
May 0 0 too few examined
Jun 0 0 too few examined
Jul 0 0 too few examined
Aug 0 0 too few examined
Sep 0 0 too few examined
Oct 0 0 too few examined
Nov 0 0 too few examined
Dec 0 0 too few examined

Peak flowering in Feb. Each bar is the share of Erythronium rostratum observations in which someone actually recorded the reproductive state and found the plant in flower, not the raw number of flowering records. That distinction matters: people observe plants far more in spring than in winter, so a bare count of flowering records partly measures when people go outside. Dividing by the number examined removes that. 181 of 234 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 9 months have fewer than 5 examined observations, so no proportion is drawn for them. This is still a global aggregate and not a forecast for your garden: the same species flowers on different dates in different hemispheres. Where a species has fewer than 30 flowering records we do not draw this chart at all. Computed from 10.15468/dl.cgje2x.

Where it actually grows measured, from 891 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -3.6 °C -0.3 °C 3.0 °C
Warmest month, mean daily high 29.2 °C 31.9 °C 33.4 °C
Annual rainfall 1,106 mm 1,309 mm 1,589 mm
Rainfall in the driest quarter 206 mm 258 mm 332 mm

It is found where winters bring light 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 891 research-grade observations of Erythronium rostratum 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. Climate from CHELSA V2.1 (Karger et al. 2017); occurrences from 10.15468/dl.cgje2x.

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. Wikidata. common name (P1843), joined on the World Flora Online identifier (P7715). CC0. 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.