26g. CAREX Linnaeus sect. PHYSOGLOCHIN Dumortier, Fl. Belg. 145. 1827.
Theodore S. Cochrane
Carex sect. Dioicae (Tuckerman) Pax
Plants loosely cespitose or not, rhizomatous; rhizomes yellow-brown, long [short or lacking], slender, not more than 1.4 mm wide, mostly without persistent scales. Culms brown at base. Leaves: basal sheaths not fibrous; sheath fronts membranous; blades filiform or V-shaped in cross section when young, widest less than 1 mm wide, glabrous. Inflorescence a solitary spike; proximal bract absent; spikes unisexual or androgynous, ovoid to cylindric. Proximal pistillate scales with apex acute to acuminate or cuspidate. Perigynia appressed to usually spreading or reflexed at maturity, veined on abaxial face, veined or veinless on adaxial face, stipitate, mostly oblong-ovate [ovate to lanceolate], plano-convex or unequally biconvex in cross section, almost leathery, base rounded to broadly cuneate, with spongy tissue, margins rounded [sharp], apex abruptly contracted to beak, glabrous; beak 0.5–1 mm, with abaxial suture, weakly and sparsely serrulate, obscurely bidentulate. Stigmas 2. Achenes biconvex, almost as large as bodies of perigynia; style deciduous.
Species 4–6 (2 in the flora): arctic, boreal, and alpine regions of North America and Eurasia.
Carex sect. Physoglochin consists of six closely related taxa that are traditionally accepted as distinct species. The American-east Asian plant, C. gynocrates in the strict sense, is very closely related to C. dioica and has been treated as a major race of that species. Other species may be more morphologically distinct (e.g., C. davalliana Smith) or less so (e.g., C. redowskiana C. A. Meyer). Detailed studies of variation within and between species are needed.
Section Physoglochin was included in subg. Primocarex by G. Kükenthal (1909). Because of the close morphogical similarity and the readiness with which hybrids are formed with species of sections Foetidae and Glareosae, sect. Physoglochin is now placed in subg. Vignea by most authors (A. O. Chater 1980; T. V. Egorova 1999).