E-Flora BC: Electronic Atlas of the Flora of British Columbia

Eriophorum virginicum L.
tawny cotton-grass (tawny cottongrass)
Cyperaceae (Sedge family)

Introduction to Vascular Plants

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Distribution of Eriophorum virginicum
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Introduction

Tawny cotton-grass (a.k.a. tawny bog cotton) is an easily recognized rhizomatous (clonal) species of cotton-grass. Like other species of cotton-grass, it is mostly restricted to peatlands where it can be a prominent component. Eriophorum species in general are boreal in distribution and are mostly circumpolar. The exception is tawny cotton-grass, which is found only in eastern North America from Ontario, Quebec, and Labardor south to the Carolinas. It has been introduced in British Columbia in the Fraser delta, where it can be seen in many delta bogs, including the Lulu Island Bog, Burns Bog, and the Langley Bog. This is a late-flowering species of cotton-grass. As perianth bristles expand in this species they become tawny and brownish. It is anatomically different from other species of cotton-grass. View a video about identifying tawny cotton-grass in the field, with Tony Reznicek.

Species Information

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Illustration Source: The Illustrated Flora of British Columbia

General:
Perennial herb from rhizomes; stems solitary or few together, stiff, erect, up to 100 cm tall.

Leaves:
Sheaths brownish to purplish, persistent; blades 2-4 mm wide, flat, except at the tips.

Flowers:
Spikes several, terminal, in crowded clusters, the stalks short and nearly equal; anthers 1-1.5 mm long; involucral bracts 2 (3), unequal, leaflike, the longest greatly surpassing the inflorescence.

Fruits:
Scales coppery or brown, blunt or pointed, the midribs prominently 3- to 5-nerved; perianth bristles numerous, tawny or coppery, many times longer than the achenes; achenes 3-3.5 mm long, a third as wide.

Source: The Illustrated Flora of British Columbia

USDA Species Characteristics

Flower Colour:
Green

Blooming Period:
Indeterminate

Fruit/Seed characteristics:
Colour: Black
Present from Summer to Fall

Source: The USDA

Key to the Species and Taxonomic Notes

Key to Eriophorum

1. Spikes 2 or more, subtended by one or more leaflike involucral bracts.

2. Leaves narrow, elongate, folded or triangular in cross-section; involucral bracts solitary, shorter than the inflorescence...........................................E. gracile
2. Leaves mostly flattened, except at the tips; involucral bracts 2 or more with the longest equalling or surpassing the inflorescence.

3. Spikes crowded, the scales with several conspicuous ribs; perianth bristles orange-brown or coppery...........................................E. virginicum
3. Spikes loosely aggregated, the scales with single ribs; perianth bristles creamy-white to tawny.

4. Midribs of scales extending to the tips, sheaths green...............E. viridcarinatum
4. Midribs of scales not extending to the tips; sheaths blackish..........E. angustifolium

1. Spikes solitary, not subtended by leaflike involucral bracts.

5. Plants rhizomatous or stoloniferous, usually with solitary stems...............E. scheuchzeri
5. Plants without stolons or rhizomes, densely tufted.

6. Scales with broad, pale margins, the basal ones reflexed................E. vaginatum
6. Scales without pale margins, the basal ones not reflexed.

7. Perianth bristles pure white with silky sheen; plants 6-25 cm tall..............E. callitrix
7. Perianth bristles cream-coloured or yellow-tinged; plants 30-60 cm tall..............E. brachyantherum

Source: Illustrated Flora of British Columbia

Habitat / Range

Bogs and wet ditches in the lowland zone; rare in SW BC, known only from the Fraser River delta; introduced from E North America.

Source: The Illustrated Flora of British Columbia

Climate

The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Status Information

Origin Status	Provincial Status	BC List (Red Blue List)	COSEWIC
Exotic	SNA	Exotic	Not Listed

BC Ministry of Environment: BC Species and Ecosystems Explorer, the authoritative source for conservation information in British Columbia.

Taxonomic and Nomenclatural Links

Flora North America treatment for Cyperaceae
Flora North America treatment for Eriophorum virginicum
Genetic information (NCBI Taxonomy Database)
International Plant Names Index
Taxonomic Information from the World Flora Online
Integrated Taxonomic Information System

Additional Range and Status Information Links

Burke Museum of Natural History (Washington State records)
CalFlora
Consortium of Pacific Northwest Herbaria records
Jepson Interchange
NatureServe Explorer
USDA

Additional Photo Sources

Images From CalPhoto
UT Austin's Native Plant Database
Google Image Search
Flickr Image Search

General References

Google Scholar Search
Family References
General Botanical References for BC

Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2020. E-Flora BC: Electronic Atlas of the Plants of British Columbia [eflora.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. [Accessed: 2024-09-11 3:43:03 AM ]

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