Senna septemtrionalis(Viv.) H.S.Irwin & Barneby

arsenic bush

WFO wfo-0000163813 Accepted WFO 2026-06 8 photographs CC BY / CC BY-SA

Plate 1 figs. a–h · 8 separate observations

Senna septemtrionalis, photographed by Greg Tasney
fig. a Greg Tasney, CC BY-SA 4.0 / 2022-05-28 / obs. 201173255

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
01839070
Filed as
Senna septemtrionalis (Viv.) H.S.Irwin & Barneby
Det. by
R. C. Barneby 1989-01-01
Collected
C. E. Cerón Martínez 1988-09-07
Origin
EC
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 12 botanical countries

Regions where Senna septemtrionalis is native: Mexico Central, Mexico Gulf, Mexico Northeast, Mexico Northwest, Mexico Southeast, Mexico Southwest, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Panamá Mexico CentralMexico GulfMexico NortheastMexico NorthwestMexico SoutheastMexico SouthwestCosta RicaEl SalvadorGuatemalaHondurasNicaraguaPanamá
Native distribution of Senna septemtrionalis, 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
Mexico Central MXC NORTHERN AMERICA
Mexico Gulf MXG
Mexico Northeast MXE
Mexico Northwest MXN
Mexico Southeast MXT
Mexico Southwest MXS
Costa Rica COS SOUTHERN AMERICA
El Salvador ELS
Guatemala GUA
Honduras HON
Nicaragua NIC
Panamá PAN

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 166 in flower of 216 examined

Proportion of examined Senna septemtrionalis in flower, by month
Month In flower Examined Share 95% interval
Jan 34 40 85% 71% to 93%
Feb 19 26 73% 54% to 86%
Mar 17 20 85% 64% to 95%
Apr 18 26 69% 50% to 84%
May 12 15 80% 55% to 93%
Jun 14 18 78% 55% to 91%
Jul 6 9 67% 35% to 88%
Aug 2 3 too few examined
Sep 3 8 38% 14% to 69%
Oct 3 5 60% 23% to 88%
Nov 11 17 65% 41% to 83%
Dec 27 29 93% 78% to 98%

Peak flowering in Dec. Each bar is the share of Senna septemtrionalis 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. 166 of 216 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. One month has fewer than 5 examined observations, so no proportion is drawn for it. 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 1,372 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low 4.1 °C 8.3 °C 14.1 °C
Warmest month, mean daily high 21.8 °C 25.9 °C 29.4 °C
Annual rainfall 676 mm 1,088 mm 2,423 mm
Rainfall in the driest quarter 23 mm 118 mm 273 mm

It is barely found anywhere that freezes. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 1,372 research-grade observations of Senna septemtrionalis 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 21 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.

  • Adipera laevigata (Willd.) Britton & Rose
  • Cassia aurata (Roxb.) Vogel
  • Cassia coymbosa Ortega
  • Cassia elegans Kunth
  • Cassia floribunda var. pubescens V.Singh
  • Cassia grandiflora Desf.
  • Cassia laevigata Willd.
  • Cassia quadrangularis Zoll. & Moritzi
  • Cassia septemtrionalis Viv.
  • Cassia septentrionalis Zuccagni
  • Cassia septentrionalis Sessé & Moc.
  • Cassia vernicosa Clos
  • Chamaecassia grandiflora Link
  • Chamaecassia laevigata (Willd.) Link
  • Chamaefistula elegans (Kunth) G.Don
  • Chamaefistula laevigata (Willd.) G.Don
  • Chamaesenna laevigata (Willd.) Pittier
  • Senna aurata Roxb.
  • Senna floribunda var. pubescens (V.Singh) V.Singh
  • Senna septemtrionalis var. pubescens (V.Singh) V.Singh
  • Senna septemtrionalis var. septemtrionalis

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.