Carex sect. Bicolores
brown at base.
basal sheaths not fibrous;
sheath fronts membranous;
blades V-shaped in cross section when young, glabrous.
racemose, with 2–6 spikes, rachis of spikes papillose;
bracts usually leaflike, rarely scalelike, sheathing or sheathless;
lateral spikes pistillate, sometimes the proximal, pedunculate, prophyllate, not much longer than wide;
terminal spike staminate or gynecandrous.
ascending to spreading, weakly veined, stipitate, sometimes inflated, elliptic-obovate, biconvex to subcircular in cross section, base tapering to rounded, margins rounded, apex rounded, beakless or short-beaked, glabrous, sometimes papillose;
beak orifice entire.
biconvex, smaller than bodies of perigynia;
style deciduous.
pistillate scales with apex obtuse to acuminate.
2.
Carex sect. Bicolores
Species 4 (4 in the flora).
Carex sect. Bicolores is a small apparently natural section of uncertain relationships. The species are superficially very different, which has led some authors to allocate them to different sections. Carex aurea was included in sect. Paniceae by G. Kükenthal (1909); C. bicolor was placed in sect. Phacocystis. T. V. Egorova (1999) and A. O. Chater (1980) placed C. bicolor in sect. Atratae. The four species form a morphologic continuum with only weak discontinuities. Putative hybrids between the species appear to be fertile and can be difficult to recognise. Intersectional hybrids involving member of sect. Bicolres are uncommon. The sterile hybrid, C. garberi × C. tetanica (sect. Paniceae), occurs occasionally in meadows and shoreline fens where the two parent species grow together. K. K. Mackenzie (1931–1935, parts 2–3, pp. 230–234) included a fifth species, C. rufina Drejer, in the section. Carex rufina has a more distinct perigynium beak and a setose-serrulate distal margins of the perigynium. It is here included in sect. Phacocystis.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Lateral spikes lax, middle internodes (0.5–)0.7–1.5 mm; terminal spike usually staminate. | → 2 |
1. Lateral spikes dense, middle internodes 0.2–0.7 mm; terminal spike usually gynecandrous. | → 3 |
2. Terminal spike 0.9–2 mm wide; proximal staminate scales 2–3.5(–4) mm; perigynia bright orange when mature, divergent; pistillate scales divergent in mature fruit. | C. aurea |
2. Terminal spike (1.8–)2–3.5 mm wide; proximal staminate scales 3–6(–15) mm; perygynia whitish when mature, ascending; pistillate scales ascending. | C. hassei |
3. Terminal spike with usually not more than 1/3 of total number of flowers staminate, staminate portion 1.1–1.8 mm wide; pistillate scales usually black with green midvein, rarely dark brown. | C. bicolor |
3. Terminal spike with more than 1/3 of total number of flowers staminate, staminate portion (1.2–)1.5–3.5 mm wide; pistillate scales pale to dark brown. | → 4 |
4. Proximal staminate scales (2–)2.5–3.7 mm, apex obtuse to acute; pistillate scales medium to dark brown, apex obtuse to acute or very shortly mucronate. | C. garberi |
4. Proximal staminate scales 3–6(–15) mm, apex often long-acuminate; pistillate scales pale to medium brown, apex often mucronate or aristate. | C. hassei |
