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Senna septemtrionalis; photograph author not stated, no rights reserved CC0author not stated, no rights reserved · observed growing wild · 2026-08-27

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

Arsenic bush; Dooleyweed; Smooth senna; Wild Senna

Fabaceae · Mexico Central, Mexico Northeast +10

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Senna septemtrionalis, photograph author not stated, no rights reservedSenna septemtrionalis, photograph author not stated, no rights reservedSenna septemtrionalis, photograph (c) Keith S, some rights reserved (CC BY)Senna septemtrionalis, photograph (c) Greg Tasney, some rights reserved (CC BY-SA)Senna septemtrionalis, photograph (c) Greg Tasney, some rights reserved (CC BY-SA)Senna septemtrionalis, photograph (c) José Belem Hernández Díaz, some rights reserved (CC BY) 89 photographs ›
Habitat figures
Cold floor (1 night in 100)
3.9°C
Record low -3.3 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
26°C
Apr at the habitat CHELSA
Rain a year (median across the range)
1,198mm
8 months of 25 mm or more in the median year CHELSA
Open-sky light
29–43DLI
Lowest to highest month (DLI) CHELSA
The year in your months, northern hemisphere
  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec
Wet summers: the rain comes June to September, read as a summer growing season. rain rule, CHELSA
Northern hemisphere unless you set your site. The chart is in the habitat's months.

Summary

Senna septemtrionalis, commonly known as arsenic bush, is a species of flowering plant in the family Fabaceae and is native to Central America, the southern United States and Mexico, but is naturalised in many other countries. It is an erect shrub with pinnate leaves, with four or five pairs of egg-shaped leaflets, and yellow flowers arranged in groups of five to eight, usually with seven fertile stamens and four staminodes in each flower.

Quoted from Wikipedia, "Senna septemtrionalis", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads a summer growing season: 70% of the median year's rain (833 mm of 1,139 mm) falls in June to September, warmer than the year (wet-season mean 18.8 °C against a yearly mean of 17.2 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: December to March.

Rain

1,139 mm in the median year at the habitat, 833 mm of it June to September. Wettest month September at 222 mm, driest month December at 13 mm. Across the grid cells of the range the year's total runs 576 mm to 2,215 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,198 mm, is the year's rain at the top of the page; the 1,139 mm here is the median year's, the twelve monthly medians added, which the rain rule reads. Habitat calendar, northern hemisphere; median year across the grid cells of the range, CHELSA.

Light

Open sky over the habitat: 29 to 43 mol/m²/day across the year (daily light integral, median year across the grid cells of the range, CHELSA; the lowest 10th-percentile month across the cells is 23, the highest 90th-percentile month 48).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is 3.9 °C, the absolute minimum -3.3 °C, 6 frost nights in 44 years (NASA POWER daily minima). Warmest: the 99th-percentile day is 34.2 °C. Monthly means: the coldest month's mean nightly low 7.7 °C in January (across the grid cells of the range 5.1 °C to 12.8 °C), the warmest month's mean daily high 25.5 °C in April (median year across the grid cells of the range, CHELSA). Cold floor: 3.9 °C, which is the 1st-percentile night over 44 years at a typical spot in the range (NASA POWER).

Humidity

Relative humidity at the habitat: 56 to 68% across the year (monthly means, median year across the grid cells of the range, CHELSA). A figure about the air, saying nothing about how the plant takes water.

How this section is made

Each card states this species' habitat figures with their sources, and what two fixed rules read from them; nothing here says what the plant does, wants or tolerates. The rules · the terms.

Seasons. Read from the median year of CHELSA monthly rainfall and mean temperature across the grid cells of the range: the rain rule takes the smallest set of months carrying 70% of the rain and calls it winter when its mean is more than half a degree below the year's, summer when more than that above, and neither in between; the temperature rule, used only under 120 mm, names the cooler six months when they are at least a degree cooler than the other six. Months are shifted for the other hemisphere only where the temperature curve moves 4 °C or more and the habitat lies 10° or more from the equator. A reading of the curves, not an observation of the plant.

Rain. CHELSA monthly precipitation, median year across the grid cells of the range. The rain that falls where the species is recorded; nothing about how the plant takes water.

Light. CHELSA shortwave radiation at each envelope cell, a daily-mean flux taken to a daily total and converted at 2.07 mol of PAR per MJ. The sky over the habitat, measured; what reaches a plant under a rock, a shrub or a shade cloth is not.

Temperature. NASA POWER daily minima and maxima over 44 years at a typical spot in the range, lapse-corrected +60 m to its elevation; CHELSA monthly means, median year across the grid cells of the range. The cold floor is the 1st-percentile night named in its sentence. Not a measured survival limit for any plant in a pot.

Humidity. CHELSA relative humidity, median year across the grid cells of the range.

Climate across the habitat

Habitat months, northern hemisphere

Habitat climate of Senna septemtrionalis through the yearWarmest month April, mean daily high 26 °C; coldest month January, mean nightly low 7.7 °C; 1,139 mm of rain in the median year (the twelve monthly medians added). Medians across the range, from CHELSA; the extremes at the edge from NASA POWER. Habitat months, northern hemisphere.-10°0°10°20°30°40°frost34.2° 99th-percentile day, NASA POWER-3.3° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0100200300400mm rainDLI 29–43RH 56–68%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 134 habitat cells, CHELSA cold quarter: the three months around the coldest month's mean nightly low extremes over 44 years at a typical spot in the range, from NASA POWER, marked at the edge, in no month DLI, mol/m²/dayRH %each on its own scale
Figures by month
JanFebMarAprMayJunJulAugSepOctNovDec
Day °C20 / 17–2422 / 19–2524 / 21–2726 / 23–2925 / 23–2924 / 21–2823 / 20–2623 / 20–2622 / 20–2521 / 19–2521 / 18–2420 / 18–23
Night °C8 / 5–138 / 6–1310 / 7–1412 / 9–1614 / 11–1814 / 12–1814 / 11–1714 / 11–1714 / 11–1712 / 10–1610 / 7–148 / 6–13
Rain mm22 / 11–6616 / 10–5615 / 6–5934 / 11–8565 / 35–170194 / 85–358213 / 119–351204 / 97–342222 / 100–395114 / 38–23527 / 10–9813 / 6–64
DLI31 / 24–3336 / 29–3941 / 35–4543 / 38–4842 / 38–4738 / 32–4237 / 34–4037 / 34–3932 / 29–3531 / 27–3430 / 26–3329 / 23–32
RH %58 / 51–6856 / 49–6656 / 46–6457 / 46–6561 / 50–6666 / 57–7066 / 61–7166 / 60–7168 / 62–7265 / 58–7061 / 53–6859 / 51–68
How this section is made
Each figure is the median across the 134 grid cells holding the 174 in-range records, with the 10th–90th percentile span across those cells after the slash where it differs. A dash is a month one or more of those cells has no figure for in the grid (a variable CHELSA does not carry there), so no median is taken rather than one over fewer cells. Extremes and elevation were read at a typical spot in the range, cell 1455:1679 (17.225, -96.025). Over 44 years there: absolute minimum -3.3 °C, 1st-percentile night 3.9 °C, 99th-percentile day 34.2 °C. Normals: CHELSA V2.1 1981–2010 climatology, 0.05° cells (each the mean of ~36 1 km pixels). Across the range: median and 10th–90th percentile of each month across the 134 distinct grid cells holding 174 of the 174 in-range records; extremes and elevation at the typical cell 1455:1679 (its coldest month's mean nightly low nearest the median across cells); its position is the cell centre. Extremes: NASA POWER (MERRA-2) daily 1981–2024, cell 17.00_-96.250, lapse-corrected +60 m at 6.5 °C/km. Elevation: ETOPO 2022, 1728 m (cell mean).

Natural habitat

Native range as published by WCVP; the marker is where the records are densest and decides nothing: the climate was read across the cells of the in-range records placed well enough to read one, not at the marker.
Openly licensed records inside the range, framed on where they fall.
NativeMexico Central, Mexico Northeast, Mexico Gulf, Mexico Northwest, Mexico Southwest, Mexico Southeast, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Panama · introduced: Madeira, Ghana, Nigeria, Sierra Leone, Burundi, Cameroon, Equatorial Guinea, Gabon, Gulf of Guinea Is., Rwanda, Zaïre, Ethiopia, Kenya, Tanzania, Uganda, Angola, Malawi, Mozambique, Zambia, Zimbabwe, Cape Provinces, KwaZulu-Natal, Swaziland, Northern Provinces, Madagascar, China Southeast, Assam, East Himalaya, India, Nepal, Pakistan, Sri Lanka, West Himalaya, Myanmar, Vietnam, Jawa, Malaya, Sulawesi, Sumatera, New Guinea, Norfolk Is., New South Wales, Queensland, Kermadec Is., New Zealand North, Fiji, New Caledonia, Vanuatu, Hawaii, Cuba, Dominican Republic, Jamaica, Puerto Rico, Trinidad-Tobago, Windward Is., Venezuela, Colombia, Ecuador, Galápagos, Peru, Brazil West-Central, Brazil South · regions are the level-3 units of the World Geographical Scheme for Recording Plant Distributions, as Kew's World Checklist records ranges, some under historical names such as Yugoslavia or Czechoslovakia (how).
Map marker20.375, -100.275 · in the densest population, 171 records (59% of those in range)
Kew's description“subshrub, shrub or tree” · “seasonally dry tropical” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 290 georeferenced records inside the native range; the climate across the range on the 174 of them placed to within 10 km; the map shows only the 218 openly licensed ones, which alone would put the marker 46 km away. 950 records outside the WCVP native range not used. 116 in-range records are placed to worse than 10 km, or with no stated accuracy (admitted only as a person's observation to three decimals), and stay on the map but off the climate.
How this section is made
The map marker: the openly licensed record nearest the middle of the densest 1° population inside the densest 2° block of the 290 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Senna septemtrionalis, photograph 1did not loadSenna septemtrionalis, photograph 2did not loadSenna septemtrionalis, photograph 3did not loadSenna septemtrionalis, photograph 4did not loadSenna septemtrionalis, photograph 5did not loadSenna septemtrionalis, photograph 6did not load

Photographs: author not stated, no rights reserved · CC0 (2); (c) Keith S, some rights reserved (CC BY); (c) Greg Tasney, some rights reserved (CC BY-SA) (2); (c) José Belem Hernández Díaz, some rights reserved (CC BY).

Similar habitat climate The 6 nearest by mean daily high, mean nightly low and rain, month by month. How.

Lobelia laxiflora Lobelia laxiflora Sierra Madre lobelia Photo: CC BY, Alejandro Gómez MayaMorus celtidifolia Morus celtidifolia Texas Mulberry Photo: CC BY, Forest Botial-JarvisTagetes filifolia Tagetes filifolia Irish-lace marigold Photo: CC0, author not statedAmicia zygomeris Amicia zygomeris Yoke-leaved amicia Photo: CC0, author not statedArisaema macrospathum Arisaema macrospathum Araceae Photo: CC BY, Erick Vélez SánchezStevia ovata Stevia ovata Roundleaf candyleaf Photo: CC BY, Nicolás Baresch Uribe

Other Senna 68 in the reference

Senna acclinis Senna acclinis Rainforest Cassia Photo: CC BY-SA, Greg TasneySenna aciphylla Senna aciphylla Sprawling Cassia Photo: CC BY, Guy TaseskiSenna alata Senna alata Emperor's candlesticks Photo: CC BY, renjus boxSenna alexandrina Senna alexandrina Alexandrian senna Photo: CC BY, Karim HaddadSenna aphylla Senna aphylla Fabaceae Photo: CC BY, Guillermo DebandiSenna armata Senna armata Desert senna Photo: CC BY, Jacob SaucierSenna arnottiana Senna arnottiana Fabaceae Photo: CC BY, Morten RossSenna artemisioides Senna artemisioides Silver senna Photo: CC BY, Michelle W. （鍾偉瑋）Senna atomaria Senna atomaria Flor de San Jose Photo: CC BY, Jose Luis Leon de la LuzSenna auriculata Senna auriculata Matara-tea Photo: CC BY, Rohit NaniwadekarSenna aymara Senna aymara Fabaceae Photo: CC BY, Thomaz Ricardo Favreto SinaniSenna bacillaris Senna bacillaris Whitebark senna Photo: CC BY, scaup all 69 ›

Names & registers

Also known as Adipera laevigata; Cassia aurata; Cassia coymbosa; Cassia elegans; Cassia floribunda and 16 more. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Fabaceae
Described by
(Viv.) H.S.Irwin & Barneby
Native to
Mexico Central, Mexico Northeast, Mexico Gulf +9
Wild records
290 in range · 218 open

Every figure here is derived from public data by a stated rule and names its source; nothing about this species is written for its page by a person or by AI, apart from the marked, credited quotations. How →

Where this page came from built 2026-10-22
GBIF species record gbif.species answeredasked 2026-10-22
GBIF synonyms gbif.synonyms answeredasked 2026-10-22
GBIF common names gbif.vernacular answeredasked 2026-10-22names fetched 2026-10-22
WCVP native range wcvp.distribution answeredas of 2026-06-04
GBIF occurrence records gbif.occurrences answeredas of 2026-10-21GBIF occurrence download https://doi.org/10.15468/dl.hbdw64, of 2026-10-21; 26 records within 1 km of a botanic garden, herbarium or zoo left out (16 at a botanic garden or arboretum, 5 at a herbarium, 5 at a zoo; Wikidata's list)
Habitat climate climate answeredasked 2026-10-22
Daily extremes (NASA POWER) climate.extremes answeredasked 2026-10-22NASA POWER (MERRA-2) daily 1981–2024, cell 17.00_-96.250, lapse-corrected +60 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-22
Wikipedia wikipedia answeredasked 2026-10-22
iNaturalist photographs, wild inat.photos.wild answeredasked 2026-10-22from iNaturalist's open data of 2026-09-27: research-grade observations with an open-licence photograph, the 24 whose photographs iNaturalist received last (the open data holds no votes); filled 2026-10-22
iNaturalist photographs, cultivated inat.photos.cultivated not asked
GBIF media gbif.media answeredasked 2026-10-22
OpenAlex papers openalex not askednot yet asked for this reference; a later fill takes the papers from OpenAlex's snapshot

Every source is recorded as having answered, reported nothing, refused, failed, not been asked, or answered twice where one answer is taken (“not taken: two items answered”), and, for a source asked when this page was built, when: the figures are as the source held them that day; a source read from a file (Kew's World Checklist, a GBIF download) says "as of" the file's day instead; a row carried from an earlier build of the page names that build instead. Only “nothing to report” is ever shown as an absence. Records came from 101 datasets via GBIF.org; each carries its own licence.

Cultifolio

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