Heuchera cylindrica (Poker Alumroot)

Plate 1 figs. a–h · 8 separate observations

Heuchera cylindrica, photographed by Shane Johnson — fig. a Shane Johnson, CC0 1.0 / 2022-06-06 / obs. 204759719

Heuchera cylindrica, photographed by Braden J. Judson — fig. b Braden J. Judson, CC0 1.0 / obs. 205923655

Heuchera cylindrica, photographed by James H. Thomas — fig. c James H. Thomas, CC BY 4.0 / obs. 203723917

Heuchera cylindrica, photographed by mfeaver — fig. d mfeaver, CC BY 4.0 / obs. 203225917

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 Heuchera cylindrica, 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
Alberta	ABT	NORTHERN AMERICA
British Columbia	BRC
California	CAL
Idaho	IDA
Montana	MNT
Nevada	NEV
Oregon	ORE
Washington	WAS
Wyoming	WYO

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 695 in flower of 1,309 examined

10%

62%

73%

69%

37%

Proportion of examined Heuchera cylindrica in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	0	5	0%	0% to 43%
Feb	0	8	0%	0% to 32%
Mar	0	27	0%	0% to 12%
Apr	5	49	10%	4% to 22%
May	235	382	62%	57% to 66%
Jun	276	380	73%	68% to 77%
Jul	138	199	69%	63% to 75%
Aug	34	92	37%	28% to 47%
Sep	4	60	7%	3% to 16%
Oct	2	58	3%	1% to 12%
Nov	1	27	4%	1% to 18%
Dec	0	22	0%	0% to 15%

Peak flowering in Jun. Each bar is the share of Heuchera cylindrica 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. 695 of 1,309 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.

Where it actually grows measured, from 1,921 observations

Condition	5th percentile	Median	95th percentile
Coldest month, mean daily low	-15.5 °C	-8.5 °C	-4.8 °C
Warmest month, mean daily high	18.3 °C	25.4 °C	29.4 °C
Annual rainfall	317 mm	495 mm	1,330 mm
Rainfall in the driest quarter	46 mm	80 mm	244 mm

It is found where winters are severely cold. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 1,921 research-grade observations of Heuchera cylindrica 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 28 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.

Heuchera alpina (S.Watson) Blank.
Heuchera columbiana Rydb.
Heuchera cylindrica f. valida Rosend., Butters & Lakela
Heuchera cylindrica var. alpina S.Watson
Heuchera cylindrica var. glabella Wheelock
Heuchera cylindrica var. orbicularis (Rosend., Lakela & Lakela) Calder & Savile
Heuchera cylindrica var. ovalifolia (Nutt.) Wheelock
Heuchera cylindrica var. septentrionalis Rosend., Butters & Lakela
Heuchera cylindrica var. suksdorfii (Rydb.) Dorn
Heuchera cylindrica var. typica Rosend., Butters & Lakela
Heuchera glabella Torr. & A.Gray
Heuchera glabella var. columbiana (Rydb.) Piper
Heuchera glabella var. suksdorfii (Rydb.) Rosend.
Heuchera ovalifolia Nutt.
Heuchera ovalifolia var. alpina (S.Watson) Rosend.
Heuchera ovalifolia var. orbicularis Rosend., Butters & Lakela
Heuchera ovalifolia var. thompsonii Rosend., Butters & Lakela
Heuchera ovalifolia var. typica Rosend., Butters & Lakela
Heuchera saxicola E.E.Nelson
Heuchera suksdorfii Rydb.
Heuchera suksdorfii f. ribesoides Rosend., Butters & Lakela
Heuchera suksdorfii f. sandbergui Rosend., Butters & Lakela
Heuchera suksdorfii f. typica Rosend., Butters & Lakela
Holochloa cylindrica (Douglas) Nutt.

and 4 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.
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.