Rhododendron simsii

Plate 1 figs. a–h · 8 separate observations

Rhododendron simsii, photographed by 葉子 — fig. b 葉子, CC0 1.0 / obs. 109096072

Rhododendron simsii, photographed by Pedro Henrique Maloso Ramos — fig. c Pedro Henrique Maloso Ramos, CC BY 4.0 / obs. 20298258

Rhododendron simsii, photographed by Aaron Liston — fig. d Aaron Liston, CC BY 4.0 / obs. 9699521

Rhododendron simsii, photographed by Diogo Luiz — fig. e Diogo Luiz, CC BY 4.0 / obs. 52246891

Rhododendron simsii, photographed by 胡正恆(Jackson Hu) — fig. g 胡正恆(Jackson Hu), CC BY 4.0 / obs. 196515715

Rhododendron simsii, photographed by portioid — fig. h portioid, CC BY 4.0 / obs. 115734493

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 9 botanical countries

Native distribution of Rhododendron simsii, 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. Regions too small to draw at this scale are marked with a dot.

Region	TDWG code	Continent
China South-Central	CHC	ASIA-TEMPERATE
China Southeast	CHS
Nansei-shoto	NNS
Taiwan	TAI
Tibet	CHT
Laos	LAO	ASIA-TROPICAL
Myanmar	MYA
Thailand	THA
Vietnam	VIE

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 55 in flower of 58 examined

100%

95%

83%

Proportion of examined Rhododendron simsii in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	3	3	too few examined
Feb	2	2	too few examined
Mar	13	13	100%	77% to 100%
Apr	20	21	95%	77% to 99%
May	2	2	too few examined
Jun	3	3	too few examined
Jul	1	1	too few examined
Aug	2	2	too few examined
Sep	1	2	too few examined
Oct	3	3	too few examined
Nov	0	0	too few examined
Dec	5	6	83%	44% to 97%

Peak flowering in Mar. Each bar is the share of Rhododendron simsii 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. 55 of 58 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 9 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 404 observations

Condition	5th percentile	Median	95th percentile
Coldest month, mean daily low	-1.0 °C	11.4 °C	17.9 °C
Warmest month, mean daily high	24.4 °C	28.9 °C	32.6 °C
Annual rainfall	1,408 mm	2,218 mm	3,071 mm
Rainfall in the driest quarter	81 mm	130 mm	316 mm

It is found where winters bring light 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 404 research-grade observations of Rhododendron simsii 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 23 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.

Azalea fimbriata Dum.Cours
Azalea indica var. simsii (Planch.) Rehder
Azalea indica var. simsii (Planch.) L.H.Bailey
Azalea prolifera Poit.
Azalea simsii (Planch.) H.F.Copel.
Azalea vittata (Planch.) Dum.Cours
Azalea vittatopunctata Lem.
Rhododendron annamense Rehder
Rhododendron bellum W.P.Fang & G.Z.Li
Rhododendron bicolor P.C.Tam
Rhododendron breynii Planch.
Rhododendron calleryi Planch.
Rhododendron indicum var. formosanum Hayata
Rhododendron indicum var. ignescens Sweet
Rhododendron indicum var. puniceum Sweet
Rhododendron indicum var. simsii (Planch.) Maxim.
Rhododendron petilum P.C.Tam
Rhododendron simsii subsp. mesembrinum Rehder
Rhododendron simsii var. bellum (W.P.Fang & G.Z.Li) G.Z.Li
Rhododendron simsii var. simsii
Rhododendron simsii var. strigosistylum G.Z.Li
Rhododendron viburnifolium W.P.Fang
Rhododendron vittatum (Fortune) Planch.

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.