Conyza ramosissimaCronquist

dwarf horseweed

WFO wfo-0000003552 Accepted WFO 2026-06 8 photographs CC BY / CC BY-SA

Plate 1 figs. a–h · 8 separate observations

Conyza ramosissima, photographed by Jeff D Hansen
fig. a Jeff D Hansen, CC BY 4.0 / 2021-09-23 / obs. 159254839
Conyza ramosissima, photographed by Clay
fig. b Clay, CC BY 4.0 / obs. 156160045
Conyza ramosissima, photographed by Brian Finzel
fig. c Brian Finzel, CC BY-SA 4.0 / obs. 142384342
Conyza ramosissima, photographed by Jeff D Hansen
fig. d Jeff D Hansen, CC BY 4.0 / obs. 89633624
Conyza ramosissima, photographed by Clay
fig. e Clay, CC BY 4.0 / obs. 49292800
Conyza ramosissima, photographed by Sam Kieschnick
fig. f Sam Kieschnick, CC BY 4.0 / obs. 8844268
Conyza ramosissima, photographed by Brian Finzel
fig. g Brian Finzel, CC BY-SA 4.0 / obs. 181904461
Conyza ramosissima, photographed by Sam Kieschnick
fig. h Sam Kieschnick, CC BY 4.0 / obs. 166690003

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.

Native range 20 botanical countries

Regions where Conyza ramosissima is native: Alabama, Arkansas, Illinois, Indiana, Iowa, Kansas, Louisiana, Minnesota, Mississippi, Missouri, Nebraska, New Mexico, North Dakota, Ohio, Oklahoma, Pennsylvania, South Dakota, Texas, Virginia, Wisconsin AlabamaArkansasIllinoisIndianaIowaKansasLouisianaMinnesotaMississippiMissouriNebraskaNew MexicoNorth DakotaOhioOklahomaPennsylvaniaSouth DakotaTexasVirginiaWisconsin
Native distribution of Conyza ramosissima, 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
Illinois ILL
Indiana INI
Iowa IOW
Kansas KAN
Louisiana LOU
Minnesota MIN
Mississippi MSI
Missouri MSO
Nebraska NEB
New Mexico NWM
North Dakota NDA
Ohio OHI
Oklahoma OKL
Pennsylvania PEN
South Dakota SDA
Texas TEX
Virginia VRG
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.

Where it actually grows measured, from 295 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -6.3 °C 3.3 °C 4.0 °C
Warmest month, mean daily high 28.9 °C 34.0 °C 34.8 °C
Annual rainfall 835 mm 1,007 mm 1,319 mm
Rainfall in the driest quarter 85 mm 183 mm 272 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 295 research-grade observations of Conyza ramosissima 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.

Also published as 1 synonym

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.

  • Erigeron divaricatus Michx.

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.