Carex leptalea (Bristle-stalked Sedge)
|Also known as:|
|Habitat:||part shade, shade; moist to wet; bogs, swamps, fens, woods, thickets, peatlands, wet meadows, swales|
|Fruiting season:||June - August|
|Plant height:||4 to 28 inches|
|Wetland Indicator Status:||GP: OBL MW: OBL NCNE: OBL|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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A single spike less than 2/3 inch long at the top of the stem, with staminate (male) flowers at the tip and pistillate (female) flowers below (androgynous), mostly crowded together. A bract at the base of the spike is absent, however, the scale subtending the lowest flower is often elongated and may be half as long as the spike or sometimes more.
Leaves and stems:
1 or 2 leaves are alternately attached to the stem near the base, each up to 10 inches long, up to 1.3 mm wide, about as wide as and shorter than the flowering stems, hairless, soft and floppy, mostly flat or sometimes folded.
Bases are wrapped in a brown sheath that is not fibrous, old leaf bases often persisting to the next season. Stems are erect to ascending, 3-sided, very slender, elongating up to 28 inches at maturity and remain mostly longer than the leaves. Plants form loose clumps and typically create colonies from slender, creeping rhizomes.
Fruit develops in late spring to mid-summer, the spike forming a cluster of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. The scales of staminate flowers tightly wrap around the stalk at the tip. Each spike contains 2 to 9 fruits, erect/appressed and loosely to strongly overlapping.
Pistillate scales are broadly egg-shaped with a pointed tip, whitish to brown with a green midvein, red dotted, mostly about half as long as the perigynia, the scale of the lowest perigynia may be rather longer with the midvein extending to an awn. Perigynia are 2.4 to 3.5(4.9+) mm long, .8 to 1.3 mm wide, 2-ribbed with numerous feint vens (more visible when mature and dry), green to yellowish when mature, oblong-elliptic, narrowed at the base, rounded at the tip and beakless but with a small dimple at the tip, and loosely wrap the achene. Achenes are 1.3 to 1.9 mm long, .7 to 1.2 mm wide, oblong to somewhat urn-shaped, 3-sided and may be sharply angled.
Carex leptalea has the widest geographical range of all Carex species in North America, found across the continent in shady bogs, swamps, wet meadows, alder thickets, peatlands, and moist woods, often creating dense mats.
Carex is a large genus, with over 600 species in North America and 150+ in Minnesota alone. They are grouped into sections, the species in each group having common traits. Carex letpalea is the lone member of the Leptocephalae section in Minnesota; some of the section's common traits are: clump forming and rhizomatous, basal sheaths brown and not fibrous, leaves V-shaped in cross-section when young, 1 spike per stem, spike with staminate flowers at the tip (androgynous), perigynia hairless and weakly veined, perigynia beakless, achenes 3-sided.
Carex leptalea should not be confused with any other sedge in Minnesota; the delicate foliage, small, single, androgynous spike with few perigynia that are appressed and beakless, and the mat-forming growth particularly in shady wet places, distinguish it from all other sedges. It is somewhat variable in length of the perigynia, shape and color of the pistillate scales, and the sharpness of angles on the achenes. Three possible subspecies are being considered, though not yet formally recognized, two of which have longer perigynia (4.7+ mm) and would be west coast or southeastern species. The most common of these forms would be considered subsp. leptalea, a more slender variation with perigynia only up to 3.5 mm long, and would be the subspecies found in Minnesota.
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- Bristle-stalked Sedge plants
- a clump of Bristle-stalked Sedge
- a mat of Bristle-stalked Sedge, with Marsh Marigold
Photos courtesy Peter M. Dziuk taken in Cook County.
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