Trichophorum alpinum (Alpine Bulrush)

Plant Info
Also known as: Hudson Bay Bulrush, Alpine Club-sedge, Alpine Leafless-Bulrush
Genus:Trichophorum
Family:Cyperaceae (Sedge)
Life cycle:perennial
Origin:native
Habitat:part shade, sun; wet; bogs, fens, wet meadows, shores, floating mats
Fruiting season:June - August
Plant height:4 to 16 inches
Wetland Indicator Status:GP: OBL MW: OBL NCNE: OBL
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: indistinct Cluster type: spike

[photo of spike] A single spike at the top of the stem, lance-elliptic in outline, 5.4 to 8 mm (to ~1/3 inch) long, with 15 to 20 florets spirally arranged, each floret subtended by a single scale. Scales are 4 to 5 mm long, blunt to pointed at the tip, yellowish to brown. Florets have 3 stamens, a 3-parted style, and white, cottony bristles that extend out beyond the scale. At the base of the spike is a single, erect bract about as long as or slightly shorter than the spike, scale-like with a prominent green midrib.

Leaves and stems: Leaf attachment: alternate Leaf type: simple

[photo of stems] Leaves are mostly basal. Stem leaves are few, near the base of the stem and have blades less than ½ inch long. Sheaths are concave at the tip. Stems are slender, 3-sided and rough-textured below the spike. Plants form loose to dense clumps and may form loose colonies. Old dead stems and basal sheaths persist to the next season.

Fruit: Fruit type: seed without plume

[photo of mature achenes] Each flower produces a single achene (seed), that drops off independently of the scale, the scales usually dropping first. Achenes are 1.2 to 1.6 mm long, brown with very fine pitting on the surface, lens-shaped in cross-section, urn-shaped in outline, rounded at the tip end and tapering at the base. Surrounding the achene are 6 flat, white bristles, up to 20 times longer than the achene.

Notes:

Alpine Bulrush is a circumboreal species of wet, marly or peaty habitats, including floating mats, bogs, sedge meadows, fens and shores and is native to parts of Europe and Asia as well as the northern latitudes of North America. Trichophorum Bulrushes, with their short stature and single terminal spike, look less like other Bulrushes and more like Spikerushes (Eloecharis species), and T. alpinum with its cottony plume resembles the Cottongrasses (Eriophorum species) even more, though the Cottongrasses usually have multiple spikes per stem and 10+ bristles per achene. The single, cottony spike and slender, 3-sided, nearly leafless stems make Alpine Bulrush fairly easy to ID. While it may form dense clumps, it is not unusual to see loose colonies of more scattered, small clumps in favorable sites.

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More photos

Photos by K. Chayka taken in Cook County. Photos by Peter M. Dziuk taken in Cook, Lake and St. Louis counties. Photos courtesy Steve Eggers taken in Wisconsin.

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Gary - Cook County
on: 2018-11-20 16:23:35

In a sunny open area in an otherwise densely treed cedar swamp growing at the edges of small pools with sundew and bog buckbean.

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