Trichophorum clintonii (Clinton's Bulrush)
|Also known as:||Clinton's Club-sedge, Clinton's Leafless-Bulrush|
|Habitat:||sun; moist to dry soil sandy or loamy soil; prairies, savannas, forest clearings, hillsides, banks|
|Fruiting season:||May - June|
|Plant height:||3 to 10 inches|
|Wetland Indicator Status:||GP: FACU MW: FACU NCNE: FACU|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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A single spike at the top of the stem, lance-elliptic in outline, 3.4 to 5.3 mm (less than ¼ inch) long, with 3 to 6 florets spirally arranged, each floret subtended by a single scale. Scales are about 3 mm long, orange-brown to brown. Florets have 3 stamens and a 3-parted style. At the base of the spike is a single, erect bract a little shorter to a little longer than the spike, scale-like with a prominent green midrib that extends to a short awn.
Leaves and stems:
Leaves are mostly basal, up to 8 inches long, less than 1 mm wide; stem leaves are few, mostly on the lower stem. Sheaths are straight across or concave at the tip; basal sheaths are orange to brown and bladeless. Stems are slender, 3-sided, rough-textured below the spike, and only a few inches tall at flowering time but extend up to 10 inches at maturity, longer than the leaves.
Plants form dense clumps, the old dead stems and sheaths persisting and building up around the clump of new growth. The dead foliage tends to have a coppery or bronze tinge, which may set it apart from other dead vegetation.
Each flower produces a single achene (seed), that drops off independently of the scale, the scales usually dropping first. Achenes are 1.5 to 2 mm long, light brown, smooth, compressed 3-sided in cross-section, urn-shaped in outline, rounded at the tip end and tapering at the base. Surrounding the achene are 3 to 6 brown bristles that are as long as or slightly shorter than the achene and minutely hairy or toothed on the tip end.
Clinton's Bulrush is a rare species in most of its US range and is currently a Threatened species in Minnesota. While elsewhere it may be found in floodplains, shores and river banks, in Minnesota habitats are mostly wet prairies, savannas and forest openings as well as the aspen parklands area in our northwest counties. According to the DNR, this species seems to have very specific habitat requirements that are in transition zones between wet and dry areas, areas that are not easily defined or located. The greatest risks in the areas where it has been found are development and invasive species, in particular Reed Canary Grass and Buckthorn. It was listed as a Special Concern species in 1996 and elevated to Threatened in 2013.
Trichophorum Bulrushes, with their short stature and single terminal spike, look less like other Bulrushes and more like Spikerushes (Eloecharis species). Spikerushes have smooth, round or compressed stems, 2 leaves per stem that are reduced to bladeless sheaths, the bract at the base of the spike is not much different from the floral scales and lacks a green midrib, and achenes usually have a cap-like appendage (tubercle) at the tip.
Clinton's Bulrush is distinguished by its single spike, the floral bract scale-like about as long as the spike with a prominent green midrib, 3-sided stem, leaves up to 8 inches long but shorter than the stem, and dense tuft of old, persistent stems and sheaths. It is most similar to Tufted Bulrush (T. cespitosum), which has grooved stems that are round in cross-section, and a single, inconspicuous stem leaf.
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Photos by K. Chayka and Peter M. Dziuk taken in Anoka County.
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