Denmoza rhodacantha

Plate 1 figs. a–h · 8 separate observations

Denmoza rhodacantha, photographed by Agustín Zarco — fig. d Agustín Zarco, CC BY 4.0 / obs. 106905533

Denmoza rhodacantha, photographed by aacocucci — fig. f aacocucci, CC BY 4.0 / obs. 57194491

Denmoza rhodacantha, photographed by Lauu — fig. g Lauu, CC BY 4.0 / obs. 180956157

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 1 botanical country

Native distribution of Denmoza rhodacantha, 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.

Region	TDWG code	Continent
Argentina Northwest	AGW	SOUTHERN AMERICA

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 86 in flower of 124 examined

67%

92%

67%

89%

56%

48%

Proportion of examined Denmoza rhodacantha in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	8	12	67%	39% to 86%
Feb	11	12	92%	65% to 99%
Mar	1	2	too few examined
Apr	1	1	too few examined
May	1	1	too few examined
Jun	0	1	too few examined
Jul	0	1	too few examined
Aug	2	4	too few examined
Sep	10	15	67%	42% to 85%
Oct	32	36	89%	75% to 96%
Nov	9	16	56%	33% to 77%
Dec	11	23	48%	29% to 67%

Peak flowering in Feb. Each bar is the share of Denmoza rhodacantha 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. 86 of 124 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 6 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.

Where it actually grows measured, from 396 observations

Condition	5th percentile	Median	95th percentile
Coldest month, mean daily low	-8.0 °C	-1.6 °C	2.6 °C
Warmest month, mean daily high	18.6 °C	23.1 °C	29.0 °C
Annual rainfall	190 mm	325 mm	478 mm
Rainfall in the driest quarter	11 mm	37 mm	80 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 396 research-grade observations of Denmoza rhodacantha 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 20 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.

Cactus coccineus Gillies ex Loudon
Cereus erythrocephalus (K.Schum.) A.Berger
Cereus rhodacanthus (Salm-Dyck) F.A.C.Weber
Cleistocactus rhodacanthus (Salm-Dyck) Lem.
Denmoza ducis-pauli (C.F.Först. ex Rümpler) Werderm. ex Backeb.
Denmoza erythrocephala (K.Schum.) A.Berger
Denmoza rhodacantha var. diamantina Slaba
Denmoza strausii var. luteispina Frič
Echinocactus coccineus Pfeiff.
Echinocactus rhodacanthus Salm-Dyck
Echinocactus rhodacanthus var. coccineus Monv. ex Labour.
Echinopsis ducis-pauli C.F.Först. ex Rümpler
Echinopsis rhodacantha (Salm-Dyck) Salm-Dyck
Echinopsis rhodocantha (Salm-Dyck) C.F.Först.
Furiolobivia ducis-pauli (C.F.Först.) Y.Itô
Lobivia ducis-pauli (C.F.Först.) Borg
Mammillaria coccinea G.Don
Pilocereus erythrocephalus K.Schum.
Pilocereus rhodacanthus Speg.
Pseudolobivia ducis-pauli (C.F.Först.) Krainz

Sourcesevery claim on this page

World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.
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.