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Scirpus atrovirens - (image 1 of 5)

Taxonomy

Family: Cyperaceae

Habitat

Common in marshy ground near streams and ponds, ditches. Calcareous fens. Swamps, wet meadows.

Associates

Asclepias incarnata, Calamagrostis canadensis, Carex vulpinoidea, Eupatorium perfoliatum, Glyceria striata, Juncus dudleyi, Leersia oryzoides, Lycopus americanus, Lythrum alatum, Mentha arvensis villosa, Mimulus ringens, Penthorum sedoides, Verbena hastata. In springy and mucky ground with Angelica atropurpurea, Carex hystericina, Eupatorium maculatum, Impatiens capensis, Lobelia siphilitica.

Distribution

Newfoundland and Quebec west to WA, south to GA, TX, and AZ.

Morphology

Herbaceous perennial from a stout rhizome, to 5' high. Leaves alternate, strap-like, dark green; lower leaf blades and sheaths distinctly nodulose-septate; stems tufted, the cauline leaves fewer than 10. Culms terete to bluntly triangular above. Bracts subtending the inflorescence conspicuous, composed of 2 or more flat or flattish blades quite unlike the culm, usually spreading or reflexed.

Inflorescence once or twice widely branched, often with axillary bulblets; spikelets numerous, crowded into dense, mostly subglobose heads, ovoid or short-cylindrical, to 8mm long.  Fruit an achene, numerous; perianth bristles more than 3, exceeding the achenes, straight or nearly so, barbed; scale persistent.

Notes

Flowers early June to early August

Wetland indicator: Obligate

Highly variable and has been split into several species by various authors.

References

Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. Second Ed.
The New York Botanical Garden. Bronx, NY
 

Swink, F. and G. Wilhelm. 1994. Plants of the Chicago Region.
Indiana Academy of Science. The Morton Arboretum. Lisle, Illinois.

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