Mammillaria formosa

Plate 1 figs. a–h · 8 separate observations

Mammillaria formosa, photographed by Sandino Guerrero — fig. b Sandino Guerrero, CC BY 4.0 / obs. 43972178

Mammillaria formosa, photographed by Alberto Wong — fig. e Alberto Wong, CC BY-SA 4.0 / obs. 20676688

Mammillaria formosa, photographed by Alejandro Gómez Maya — fig. g Alejandro Gómez Maya, CC BY 4.0 / obs. 9628152

Mammillaria formosa, photographed by Tereso Hernández Morales — fig. h Tereso Hernández Morales, CC BY 4.0 / obs. 27936384

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 3 botanical countries

Native distribution of Mammillaria formosa, 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
Mexico Gulf	MXG	NORTHERN AMERICA
Mexico Northeast	MXE
Mexico Southwest	MXS

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 31 in flower of 95 examined

100%

50%

73%

11%

Proportion of examined Mammillaria formosa in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	5	5	100%	57% to 100%
Feb	6	12	50%	25% to 75%
Mar	16	22	73%	52% to 87%
Apr	1	3	too few examined
May	1	2	too few examined
Jun	0	12	0%	0% to 24%
Jul	0	2	too few examined
Aug	1	9	11%	2% to 44%
Sep	0	2	too few examined
Oct	0	17	0%	0% to 18%
Nov	0	7	0%	0% to 35%
Dec	1	2	too few examined

Peak flowering in Jan. Each bar is the share of Mammillaria formosa 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. 31 of 95 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 5 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 151 observations

Condition	5th percentile	Median	95th percentile
Coldest month, mean daily low	0.5 °C	6.2 °C	8.9 °C
Warmest month, mean daily high	22.3 °C	27.7 °C	30.2 °C
Annual rainfall	301 mm	430 mm	643 mm
Rainfall in the driest quarter	32 mm	39 mm	57 mm

It is found where winters are cool but frost is light or absent. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 151 research-grade observations of Mammillaria formosa 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 40 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 bispinus J.M.Coult.
Cactus formosus (Galeotti ex Scheidw.) Kuntze
Cactus sempervivi (DC.) Kuntze
Cactus tetracentrus (Salm-Dyck) Kuntze
Mammillaria arroyensis Repp.
Mammillaria bachmannii Boed.
Mammillaria brongniartii Salm-Dyck
Mammillaria caerulea R.T.Craig
Mammillaria caput-medusae Otto ex Pfeiff.
Mammillaria caput-medusae var. centrispina Salm-Dyck
Mammillaria caput-medusae var. crassior Salm-Dyck
Mammillaria caput-medusae var. tetracantha Salm-Dyck
Mammillaria chionocephala J.A.Purpus
Mammillaria diacantha Lem.
Mammillaria diacantha J.N.Haage ex Steud.
Mammillaria eumorpha Repp. ex Tamegger & R.Knees
Mammillaria formosa var. dispicula Monv. ex Labour.
Mammillaria formosa var. gracilispina Monv. ex Labour.
Mammillaria formosa var. laevior Monv. ex Labour.
Mammillaria formosa var. microthele (Muehlenpf. & Tiegel) Salm-Dyck
Mammillaria microthele Muehlenpf. & Tiegel
Mammillaria microthele var. brongniartii Salm-Dyck
Mammillaria pseudocrucigera R.T.Craig
Mammillaria ritteriana Boed.

and 16 more.

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.