Rhynchospora capillacea (Needle Beaksedge)

Plant Info
Also known as: Hair-like Beakrush, Horned Beakrush
Genus:Rhynchospora
Family:Cyperaceae (Sedge)
Life cycle:perennial
Origin:native
Status:
  • State Threatened
Habitat:sun; wet sandy or peaty soil; calcareous fens, spring fens, marly pools
Fruiting season:July - September
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

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Flower: Flower shape: indistinct Cluster type: spike

[photo of spikelet clusters] One or 2 (rarely 3) clusters, the terminal cluster generally elliptic in outline, sometimes inverted cone-shaped, loosely arranged with 2 to 10 erect to ascending, brown to reddish-brown spikelets (flower clusters). Lateral clusters are smaller and well-separated from the terminal cluster. Each cluster is on an erect stalk with a leaf-like bract at the base, the bract typically exceeding the attending cluster.

[close-up of flowering spikelets] Spikelets are stalkless or nearly so, 6 to 7 mm long (~¼ inch), narrowly elliptic to spindle-shaped, pointed at the tip, with 1 to 4 perfect flowers (both male and female parts), each subtended by a scale; the lowest scale is often empty and somewhat smaller than the fertile scales. Flowers have 3 stamens and a 2-parted style. Scales are about 4 mm long, lance-shaped, rounded or pointed at the tip, the midrib sometimes extended at the tip, and are tightly appressed to the spikelet.

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

[photo of leaves and stems] Leaves are alternate and basal, erect to ascending to arching, hairless, wiry with rolled-in edges (involute), less than .5 mm wide, shorter than the flowering stem and the upper stem leaves usually not over-topping the terminal cluster. Sheaths are closed, more or less straight across at the tip, translucent green and membranous on the front. Stems are very slender, 1.5 mm diameter or less, erect to curved, unbranched, angular with a few ribs, hairless, green, leafy, and multiple from the base forming clumps, sometimes forming mats.

Fruit: Fruit type: seed without plume

[photo of scales and achenes] Spikelets produce 1 to 4 achenes (seeds), 2.5 to 3 mm long, flattened lens-shaped, elliptic in outline, the persistent style forming a narrowly triangular beak .5 to 1.2 mm long, and tapering at the base to a stalk-like appendage (stipe). Surrounding the base are 6 barbed bristles all more or less equal in length and about as long as or slightly longer than the achene, including the beak, the barbs all downward pointing or occasionally absent altogether.

Notes:

Rhynchospora capillacea is an uncommon sedge in Minnesota, found in calcareous fens in our prairie regions and spring fens in the northern forest region. According to the DNR, its preferred calcareous fen habitat is a rarity in itself, highly susceptible to hydrology changes caused by agriculture and other human activities, even from miles away. R. capillacea was listed as a Threatened species in 1984.

Rhynchospora capillacea is a fairly distinctive species, very slender with small clusters of few-flowered, spindle-shaped, red-brown spikelets, and thread-like leaves and stems. It may go unnoticed unless you're looking for it. It may be mistaken for one of the other Rhynchospora species in Minnesota, most of which have broader, flat leaves (at least at the base), stouter stems, and more hemispheric clusters with more numerous spikelets. R. fusca is most similar, also having slender stems and slender, involute leaves, but leaves are broader (to 1.5mm), achenes lack the stalk-like base, the barbs on its achene bristles point upward rather than downward (good magnification required to see), and the ranges of these two species do not generally overlap, with R. fusca mostly limited to the Arrowhead region and the patterned fens of northern Beltrami County.

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More photos

Photos by K. Chayka taken in Mahnomen County. Photos by Peter M. Dziuk taken in Mahnomen and Pope counties. Photos courtesy Steve Eggers taken in Jackson County.

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