Carex wahuensisC.A.Mey.

Oahu sedge

WFO wfo-0000352648 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h · 8 separate observations

Carex wahuensis, photographed by Kevin Faccenda
fig. a Kevin Faccenda, CC BY 4.0 / 2022-06-02 / obs. 204044246

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.

The specimen a real sheet, in a real collection

Herbarium
The New York Botanical Garden
Accession
201725
Filed as
Carex wahuensis subsp. wahuensis
Det. by
P. Jiménez Mejías 2015-01-01
Collected
C. R. Annable 1999-02-19
Origin
US
The sheet
View the digitised specimen (CC BY 4.0)

A real pressed plant, in a real collection, under the accession number above. Not an illustration of one. The holding institution does not serve this sheet’s image to third parties, so there is no photograph here. The record is real and the link goes to it. Where we hold no openly licensed sheet for a species this section is simply absent, and where a sheet never recorded who determined it, that field stays empty rather than being filled in. Roughly half of all herbarium sheets never recorded a determiner, which is ordinary.

Native range 9 botanical countries

Regions where Carex wahuensis is native: China North-Central, China Southeast, Japan, Kazan-retto, Korea, Nansei-shoto, Ogasawara-shoto, Taiwan, Hawaii China North-CentralChina SoutheastJapanTaiwanHawaii KoreaNansei-shoto
Native distribution of Carex wahuensis, 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.
RegionTDWG codeContinent
China North-Central CHN ASIA-TEMPERATE
China Southeast CHS
Japan JAP
Kazan-retto KZN
Korea KOR
Nansei-shoto NNS
Ogasawara-shoto OGA
Taiwan TAI
Hawaii HAW PACIFIC

Not drawn on the map: Kazan-retto, Ogasawara-shoto. We hold no public-domain boundary for these regions, so they are listed rather than guessed at.

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 72 in flower of 192 examined

Proportion of examined Carex wahuensis in flower, by month
Month In flower Examined Share 95% interval
Jan 8 22 36% 20% to 57%
Feb 17 29 59% 41% to 74%
Mar 12 28 43% 27% to 61%
Apr 10 19 53% 32% to 73%
May 3 14 21% 8% to 48%
Jun 4 18 22% 9% to 45%
Jul 1 16 6% 1% to 28%
Aug 1 12 8% 1% to 35%
Sep 0 6 0% 0% to 39%
Oct 3 7 43% 16% to 75%
Nov 7 12 58% 32% to 81%
Dec 6 9 67% 35% to 88%

Peak flowering in Dec. Each bar is the share of Carex wahuensis 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. 72 of 192 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 233 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low 6.8 °C 19.0 °C 21.2 °C
Warmest month, mean daily high 20.0 °C 25.1 °C 27.8 °C
Annual rainfall 779 mm 1,254 mm 3,619 mm
Rainfall in the driest quarter 94 mm 184 mm 617 mm

It is barely found anywhere that freezes. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 233 research-grade observations of Carex wahuensis 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 27 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.

  • Carex bongardii Boott
  • Carex bongardii var. robusta Franch. & Sav.
  • Carex boninensis Koidz.
  • Carex boottiana Hook. & Arn.
  • Carex boottiana var. bracteosa C.B.Clarke
  • Carex erythrolepis Kük.
  • Carex nuptialis Boott
  • Carex oahuensis Hillebr.
  • Carex oahuensis f. bracteosa C.B.Clarke
  • Carex oahuensis var. angustior Kük.
  • Carex oahuensis var. bongardii Franch. & Sav.
  • Carex oahuensis var. boottiana (Hook. & Arn.) Kük.
  • Carex oahuensis var. meyeri Franch. & Sav.
  • Carex oahuensis var. robusta Franch. & Sav.
  • Carex putuoensis S.Yun Liang
  • Carex qingdaoensis F.Z.Li & S.J.Fan
  • Carex reflexistyla Hayata
  • Carex sakonis T.Koyama
  • Carex stupenda H.Lév. & Vaniot
  • Carex stupenda var. bracteosa (C.B.Clarke) Koidz.
  • Carex stupenda var. robusta (Franch. & Sav.) Nakai
  • Carex wahuensis subsp. herbstii T.Koyama
  • Carex wahuensis subsp. rubiginosa (R.W.Krauss) T.Koyama
  • Carex wahuensis var. meyeri Franch. & Sav.

and 3 more.

Sourcesevery claim on this page

  1. World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
  2. iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.
  3. Wikidata. common name (P1843), joined on the World Flora Online identifier (P7715). CC0. Retrieved 2026-07-13.
  4. 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.