44 photographs › At a glance
- Jan
- Feb
- Mar
- Apr
- May, shaded
- Jun, shaded
- Jul, shaded
- Aug, shaded
- Sep, shaded
- Oct, shaded
- Nov
- Dec
About the genus · Vernonia
Vernonia is a genus of about 350 species of forbs and shrubs in the family Asteraceae. Some species of this genus are known as ironweeds. Some species are edible and of economic value. More on Wikipedia ›
Quoted from Wikipedia, "Vernonia", CC BY-SA 4.0.
Cultivation
Seasons
The rain rule reads a summer growing season: 70% of the median year's rain (275 mm of 391 mm) falls in May to October, warmer than the year (wet-season mean 25.3 °C against a yearly mean of 19.2 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: November to April.
Rain
391 mm in the median year at the habitat, 275 mm of it May to October. Wettest months (3 at 47 mm), driest month December at 12 mm. Across the grid cells of the range the year's total runs 265 mm to 583 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 397 mm, is the year's rain at the top of the page; the 391 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: 23 to 46 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 21, the highest 90th-percentile month 49).
Warmth and air
Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -4.5 °C, the absolute minimum -11.3 °C, 986 frost nights in 44 years, 22.4 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 41.3 °C. Monthly means: the coldest month's mean nightly low 4.2 °C in January (across the grid cells of the range 3.5 °C to 5.0 °C), the warmest month's mean daily high 33.6 °C in July and August (median year across the grid cells of the range, CHELSA). Cold floor: -4.5 °C, which is the 1st-percentile night over 44 years at a typical spot in the range (NASA POWER).
Relative humidity at the habitat: 47 to 54% 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 +44 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
Mean daily high from 17 °C in Jan to 34 °C in Jul and Aug; mean nightly low from 4 °C in Jan to 22 °C in Jun, Jul and Aug. The cold quarter, Dec to Feb, is the three months around the coldest month's mean nightly low. 391 mm of rain in the median year (the twelve monthly medians added), the wettest months (3 at 47 mm). The bands show the 10th to 90th percentile across 7 habitat cells. Over 44 years at a typical spot in the range (NASA POWER) the absolute minimum was -11.3 °C and the 99th-percentile day 41.3 °C; neither is dated to a month. Beneath: daily light integral and relative humidity through the year, each on its own scale.
Figures by month
| Figure | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Day °C | 17 / 17–19 | 20 / 19–23 | 24 / 23–27 | 28 / 26–31 | 31 / 29–35 | 33 / 30–36 | 34 / 30–35 | 34 / 29–35 | 31 / 27–32 | 26 / 25–29 | 21 / 20–24 | 18 / 17–20 |
| Night °C | 4 / 4–5 | 6 / 5–7 | 10 / 8–10 | 14 / 12–15 | 18 / 16–19 | 22 / 19–22 | 22 / 19–23 | 22 / 19–23 | 20 / 17–20 | 15 / 13–16 | 9 / 8–10 | 5 / 4–6 |
| Rain mm | 16 / 12–18 | 20 / 9–22 | 20 / 9–24 | 28 / 15–39 | 47 / 26–71 | 47 / 35–83 | 47 / 38–78 | 44 / 39–89 | 44 / 29–71 | 46 / 30–61 | 20 / 12–22 | 12 / 9–14 |
| DLI | 25 / 23–26 | 31 / 29–32 | 38 / 36–40 | 44 / 43–46 | 46 / 44–49 | 46 / 45–48 | 45 / 44–46 | 42 / 41–43 | 37 / 36–38 | 31 / 30–33 | 26 / 24–27 | 23 / 21–23 |
| RH % | 51 / 50–52 | 48 / 47–51 | 47 / 45–50 | 47 / 43–49 | 51 / 46–53 | 53 / 48–54 | 53 / 49–54 | 52 / 50–55 | 54 / 51–57 | 54 / 50–54 | 50 / 49–53 | 51 / 49–52 |
How this section is made
Natural habitat
How this section is made
Photographs
Photographs: (c) Eric Knight, some rights reserved (CC BY) (3); (c) Joseph Aubert, some rights reserved (CC BY) (3).
Related
Similar habitat climate The 6 nearest by mean daily high, mean nightly low and rain, month by month. How.
Coryphantha echinus Cactaceae Photo: CC BY, waldo_jeffers
Opuntia strigil Marble-fruit Prickly-pear Photo: CC BY-SA, Turner Brockman
Yucca thompsoniana Trans-Pecos Yucca Photo: CC BY, CK2AZ
Parthenium confertum Gray's feverfew Photo: CC BY, IDClaire Verbena racemosa Verbenaceae 
Acleisanthes longiflora Angel's trumpets Photo: CC BY, Michelle W. （鍾偉瑋）Other Vernonia 14 in the reference
Vernonia acaulis Stemless ironweed Photo: CC0, author not stated
Vernonia angustifolia Tall ironweed Photo: CC BY, Athena Philips
Vernonia arkansana Arkansas ironweed Photo: CC BY, haydenmolo
Vernonia baldwinii Western ironweed Photo: CC BY, F. LaBry
Vernonia blodgettii Florida ironweed Photo: CC BY, Tom Field
Vernonia fasciculata Prairie ironweed Photo: CC0, author not stated
Vernonia gigantea Giant ironweed Photo: CC BY, Nathan Aaron
Vernonia glauca Broadleaf ironweed Photo: CC0, author not stated Vernonia kenteocephala Asteraceae 
Vernonia lettermannii Lettermann's ironweed Photo: Public domain, Daderot
Vernonia lindheimeri Woolly ironweed Photo: CC0, author not stated
Vernonia missurica Missouri ironweed Photo: CC BY, Skyler Principe all 15 ›Names & registers
The record
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 answeredasked 2026-10-22gbif.synonyms answeredasked 2026-10-22gbif.vernacular answeredasked 2026-10-22names fetched 2026-10-22wcvp.distribution answeredas of 2026-06-04gbif.occurrences answeredasked 2026-10-22GBIF occurrence download https://doi.org/10.15468/dl.hbdw64, of 2026-10-21; 1 record of GBIF's key 5702236, Vernonia lindheimeri var. leucophylla Larsen (Kew's file holds it as Vernonia lindheimeri var. leucophylla Larsen (synonym under Vernonia larseniae B.L.King & S.B.Jones)): GBIF occurrence search API; 1 record within 1 km of a botanic garden, herbarium or zoo left out (1 at a botanic garden or arboretum; Wikidata's list)climate answeredasked 2026-10-22climate.extremes answeredasked 2026-10-22NASA POWER (MERRA-2) daily 1981–2024, cell 30.00_-102.500, lapse-corrected +44 m at 6.5 °C/kmwikidata answeredasked 2026-10-22IPNI and POWO linked by Kew's number for Vernonia larseniae B.L.King & S.B.Jones (the item's: IPNI 293952-2, POWO 258661-1)wikipedia nothing to reportasked 2026-10-22inat.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 2026-10-22inat.photos.cultivated not askedgbif.media answeredasked 2026-10-22none of the photographs on this page is credited to GBIF: those shown are other sources', and GBIF's were the same photographs or were set aside by the photograph rulesopenalex not askednot yet asked for this reference; a later fill takes the papers from OpenAlex's snapshotEvery 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 5 datasets via GBIF.org; each carries its own licence.