Calotropis procera (roostertree)

Plate 1 figs. a–h · 8 separate observations

Calotropis procera, photographed by Mitch Van Dyke — fig. a Mitch Van Dyke, CC BY 4.0 / 2022-03-26 / obs. 187293815

Calotropis procera, photographed by bungelina — fig. b bungelina, CC BY 4.0 / obs. 186735992

Calotropis procera, photographed by Surabhi Srivastava — fig. c Surabhi Srivastava, CC BY 4.0 / obs. 187469579

Calotropis procera, photographed by Enrico Tomschke — fig. d Enrico Tomschke, CC BY 4.0 / obs. 182071949

Calotropis procera, photographed by Светлана Царахова — fig. e Светлана Царахова, CC0 1.0 / obs. 181530576

Calotropis procera, photographed by John Lyden — fig. f John Lyden, CC BY 4.0 / obs. 179586886

Calotropis procera, photographed by Hugo Innes — fig. g Hugo Innes, CC BY 4.0 / obs. 179714989

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.

Flowering 1,242 in flower of 1,698 examined

76%

66%

81%

79%

77%

79%

70%

83%

62%

68%

61%

65%

Proportion of examined Calotropis procera in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	95	125	76%	68% to 83%
Feb	101	152	66%	59% to 73%
Mar	153	190	81%	74% to 86%
Apr	213	269	79%	74% to 84%
May	139	180	77%	71% to 83%
Jun	77	97	79%	70% to 86%
Jul	69	98	70%	61% to 79%
Aug	82	99	83%	74% to 89%
Sep	72	116	62%	53% to 70%
Oct	78	114	68%	59% to 76%
Nov	78	127	61%	53% to 69%
Dec	85	131	65%	56% to 73%

Peak flowering in Aug. Each bar is the share of Calotropis procera 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. 1,242 of 1,698 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 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.

Also published as 14 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.

Apocynum syriacum S.G.Gmel.
Apocynum syriacum Garsault
Asclepias gigantea Willd.
Asclepias patula Decne.
Asclepias procera Aiton
Calotropis gigantea var. procera (Aiton) P.T.Li
Calotropis hamiltonii Wight
Calotropis heterophylla Wall.
Calotropis inflexa Chiov.
Calotropis persica Gand.
Calotropis procera subsp. hamiltonii (Wight) Ali
Calotropis syriaca (S.G.Gmel.) Woodson
Calotropis wallichii Wight
Madorius procerus (Aiton) Kuntze

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.
Wikidata. common name (P1843), joined on the World Flora Online identifier (P7715). CC0. Retrieved 2026-07-13.

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. It has no native range either: Kew's checklist does not cover this taxon.