Chestnut Sedge

Hybrids between Carex castanea and C. arcata (= C. ×knieskernii) occur quite frequently across the overlapping ranges of the parental species, in roadside ditches near cedar swamps and disturbed areas in deciduous forests, where the two parental species can often be found in close proximity. Carex castanea also hybridizes rarely with C. debilis var. rudgei and probably also with C. gracillima, although the latter hybrid has not been confirmed. The length of the proximal inflorescence bract and its sheath are strongly dependent on location on the culm: If the proximal spike is positioned low on the culm, the blade is leaflike with an obvious but short sheath; if positioned more distally, the blade is reduced to an auriculate awn without a sheath. The chromosome number (2n = 64) reported by Á. Löve & D. Löve (1981b) is probably erroneous.

Plants with short rhizomes, loosely cespitose. Culms dark maroon at base; flowering stems 40–90 cm, much longer than leaves at maturity, 0.5–1 mm thick, sparingly pilose. Leaves: basal sheaths maroon, bladeless, pilose; others grading from maroon to green on back, pale to chestnut brown-hyaline and usually red dotted on front, ciliate at apex; blades flat, 2.5–9 mm wide, pilose on both surfaces, sparsely so adaxially, margins smooth or ciliate. Inflorescences: peduncles of lateral spikes capillary, 10–20 mm, glabrous or pubescent; peduncle of terminal spike erect, 3–5 mm; proximal bracts hyaline, reduced to green awn or less often leaflike and 0.3–1.5 mm wide; sheaths usually less than 3 mm (to 10 mm). Lateral spikes 2–4, 1 per node, mostly near apex but not crowded, drooping at maturity, pistillate with 10–40 perigynia attached 1 mm apart, narrowly cylindric, 8–25 × 4–5 mm. Terminal spike staminate, sessile or pedunculate, 10–30 × 1.4–3 (4) mm. Pistillate scales hyaline suffused with chestnut with broad green midrib, ovate, shorter to nearly as long as mature perigynia, apex acute to cuspidate, awns less than 1 mm, often ciliate distally. Perigynia light green, usually red dotted, 2-ribbed and 5–7-veined, at least proximally and abaxially, loosely enveloping achene, ellipsoid, 2.5–5 × 1.3–2.5 mm, membranous, base acute, apex tapering to beak, glabrous; beak bidentate to 1.5 mm, teeth 0.5 mm, ciliate between apical teeth. Achenes substipitate, 1.5–2 × 1–1.5 mm. 2n = 44, 64.

Fruiting late spring–mid summer. Cedar swamps, rich mesic deciduous or mixed conifer-hardwood forests, mixed coniferous forests and margins, mesic meadows, often associated with calcareous soils; Man., N.B., Nfld. and Labr., N.S., Ont., Que.; Conn., Maine, Mich., Minn., N. H., N.Y., Tenn., Vt., Wis.

Carex flexilis Rudge

Carex castanea Wahl. Sv. Vet.-Akad. Nya Handl 24: 155. 1803.
Carex flexilis Rudge, Trans. Linn. Soc. 7: 98. pi. 10. f. 1. 1804. (Type from Newfoundland.) Carex blepharophora A. Gray, Ann. Lye. N. Y. 3: 237. 1835. (Type from Bridgewater, Oneida
County, New York.) Loxotretna castanea Raf. Good Book 25. 1840. (Based on Carex castanea Wahl.)
Rather loosely cespitose, the rootstocks slender but tough, purplish, growing in rather small clumps, the culms 4-9 dm. high, remotely leafy, slender, erect or often weak, much exceeding the leaves, mostly lateral and aphyllopodic, sparingly hairy, strongly purplish-tinged at base, the basal sheaths loose; sterile shoots elongate, conspicuous; leaves with well-developed blades 3 or 4 to a fertile culm, on lower half, the blades usually 5-20 cm. long, about 2.5 mm. wide, soft-hairy, flat, deep-green, those of the sterile shoots 2-4 dm. long and up to 5 mm. wide, the sheaths tight, hairy, brownish-tinged and red-dotted ventrally, the ligule poorly developed ; staminate spike erect, not overtopped by the uppermost lateral spikes, slenderly long-peduncled, linear, slender, 1.5-3 cm. long, 2-3 mm. wide, the scales oblanceolate, short-awned to acute, ciliate, yellowish-brown with green midrib and white-hyaline margins; pistillate spikes usually 2 or 3, approximate or more or less separate, drooping on very slender, glabrous or slightly pubescent peduncles about their own length, oblong-cylindric, 8-25 mm. long, 4-5 mm. wide, frequently staminate at apex, closely 10-40-flowered in several rows, the perigynia ascending; bracts very short-sheathing, the lowest leaflet-like, shorter than the culm, the upper much reduced; scales ovate, awned, cuspidate, or acuminate, ciliate-denticulate above, thin, lightchestnut-brown with green midrib and hyaline margins, about the width of but rather shorter than the perigynia; perigynia lanceolate or ovate-lanceolate, 3.5-5 mm. long, 1.25 mm. wide, triangular, not at all or scarcely inflated, glabrous, membranaceous, greenish-straw-colored, puncticulate, prominently 2-keeled and several-nerved, short-tapering at base and sessile, longer-tapering to the slender, slightly hairy, obliquely cut, hyaline-tipped beak half the length of the body, the apex shallowly bidentate, ciliate; achenes small, obovoid, 1.5 mm. long, 1 mm. wide, triangular with sides concave below and blunt angles, closely enveloped, yellowishbrown, sessile, apiculate-tipped, jointed with the straight slender style; stigmas 3, blackish, slender.
Type locality: "Hab. in America boreali, secundum herb. CI. Torneri."
Distribution: Dry thickets and on banks in calcareous regions, Newfoundland to Minnesota, and southward to Connecticut, New York, and the Great Lakes region. (Specimens examined from Newfoundland, Quebec, New Brunswick, Nova Scotia, Maine, Vermont, Connecticut, New York, Ontario, Michigan, Wisconsin, Minnesota.)

Carex castanea, known as chestnut sedge, is a species of flowering plant in the sedge family (Cyperaceae) native to North America. It is listed as endangered in Connecticut, Massachusetts, and New Hampshire. It occurs from Manitoba to the eastern seaboard in Canada and from Minnesota to New England in the United States. It is sometimes called chestnut woodland sedge or chestnut-colored sedge.