Xanthorhiza simplicissima (Shrub Yellowroot)

Plate 1 figs. a–h · 8 separate observations

Xanthorhiza simplicissima, photographed by Reid Hardin — fig. a Reid Hardin, CC BY 4.0 / 2022-05-01 / obs. 194541689

Xanthorhiza simplicissima, photographed by Leila Dasher — fig. b Leila Dasher, CC BY 4.0 / obs. 191335249

Xanthorhiza simplicissima, photographed by Brian Finzel — fig. e Brian Finzel, CC BY-SA 4.0 / obs. 187401221

Xanthorhiza simplicissima, photographed by Ken Kneidel — fig. f Ken Kneidel, CC0 1.0 / obs. 189007759

Xanthorhiza simplicissima, photographed by Zac Peterson — fig. g Zac Peterson, CC BY 4.0 / obs. 188692037

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 17 botanical countries

Native distribution of Xanthorhiza simplicissima, 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
Alabama	ALA	NORTHERN AMERICA
Florida	FLA
Georgia	GEO
Kentucky	KTY
Louisiana	LOU
Maine	MAI
Massachusetts	MAS
Mississippi	MSI
New Hampshire	NWH
New York	NWY
North Carolina	NCA
Ohio	OHI
South Carolina	SCA
Tennessee	TEN
Texas	TEX
Virginia	VRG
West Virginia	WVA

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 288 in flower of 522 examined

92%

74%

19%

13%

11%

Proportion of examined Xanthorhiza simplicissima in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	0	4	too few examined
Feb	1	2	too few examined
Mar	126	137	92%	86% to 95%
Apr	139	188	74%	67% to 80%
May	13	68	19%	12% to 30%
Jun	4	32	13%	5% to 28%
Jul	1	33	3%	1% to 15%
Aug	1	13	8%	1% to 33%
Sep	1	17	6%	1% to 27%
Oct	2	18	11%	3% to 33%
Nov	0	9	0%	0% to 30%
Dec	0	1	too few examined

Peak flowering in Mar. Each bar is the share of Xanthorhiza simplicissima 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. 288 of 522 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 3 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.

Also published as 5 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.

Xanthorhiza apiifolia L'Hér.
Xanthorhiza tinctoria Woodh.
Zanthorhiza apiifolia L'Hér.
Zanthorhiza simplicissima Marshall
Zanthorhiza tinctoria Woodf.

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.
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.