Baptisia tinctoria(L.) R.Br.

horseflyweed

WFO wfo-0001417157 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h · 8 separate observations

Baptisia tinctoria, photographed by pachips
fig. a pachips, CC BY 4.0 / 2022-06-10 / obs. 205033809

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
01527824
Filed as
Baptisia tinctoria (L.) R.Br.
Det. by
D. E. Atha 2012-01-01
Collected
D. E. Atha 2011-07-09
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 24 botanical countries

Regions where Baptisia tinctoria is native: Connecticut, Delaware, Georgia, Illinois, Indiana, Kentucky, Maine, Maryland, Massachusetts, Michigan, New Hampshire, New Jersey, New York, North Carolina, Ohio, Ontario, Pennsylvania, Rhode I., South Carolina, Tennessee, Vermont, Virginia, West Virginia, Wisconsin ConnecticutGeorgiaIllinoisIndianaKentuckyMaineMarylandMassachusettsMichiganNew HampshireNew JerseyNew YorkNorth CarolinaOhioOntarioPennsylvaniaSouth CarolinaTennesseeVermontVirginiaWest VirginiaWisconsin DelawareRhode I.
Native distribution of Baptisia tinctoria, 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. Regions too small to draw at this scale are marked with a dot.
RegionTDWG codeContinent
Connecticut CNT NORTHERN AMERICA
Delaware DEL
Georgia GEO
Illinois ILL
Indiana INI
Kentucky KTY
Maine MAI
Maryland MRY
Massachusetts MAS
Michigan MIC
New Hampshire NWH
New Jersey NWJ
New York NWY
North Carolina NCA
Ohio OHI
Ontario ONT
Pennsylvania PEN
Rhode I. RHO
South Carolina SCA
Tennessee TEN
Vermont VER
Virginia VRG
West Virginia WVA
Wisconsin WIS

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 330 in flower of 554 examined

Proportion of examined Baptisia tinctoria in flower, by month
Month In flower Examined Share 95% interval
Jan 0 7 0% 0% to 35%
Feb 0 2 too few examined
Mar 0 3 too few examined
Apr 0 2 too few examined
May 22 44 50% 36% to 64%
Jun 105 131 80% 73% to 86%
Jul 185 206 90% 85% to 93%
Aug 18 76 24% 16% to 34%
Sep 0 48 0% 0% to 7%
Oct 0 21 0% 0% to 15%
Nov 0 7 0% 0% to 35%
Dec 0 7 0% 0% to 35%

Peak flowering in Jul. Each bar is the share of Baptisia tinctoria 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. 330 of 554 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 3 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.

When it blooms, where you are 3 states

StatePeaksObservations in flower
Massachusetts Jul 83
North Carolina Jun 67
Pennsylvania Jul 67

Where it actually grows measured, from 1,989 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -8.2 °C -4.3 °C 0.9 °C
Warmest month, mean daily high 21.4 °C 27.5 °C 31.1 °C
Annual rainfall 1,021 mm 1,240 mm 1,463 mm
Rainfall in the driest quarter 200 mm 273 mm 317 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 1,989 research-grade observations of Baptisia tinctoria 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.

Also published as 7 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.

  • Baptisia gibbesii Small
  • Baptisia tinctoria (L.) Vent.
  • Baptisia tinctoria var. crebra Fernald
  • Baptisia tinctoria var. gibbesii (Small) Fernald
  • Baptisia tinctoria var. tinctoria
  • Podalyria tinctoria (L.) Lam.
  • Sophora tinctoria L.

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 BATI. 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.