Carex chathamica Petrie
Lectotype: WELT, 12104, Chatham Is, W. R. B. Oliver, selected by Hamlin (Rec. Dom. Mus., Wellington 6, 1968, 98).
Tufts stout, rigid, lfy, pale green. Culms 5–35 cm. × 1.5–3 mm., trigonous, smooth, sturdy; basal sheaths light brown. Lvs not overtopping infl., 6–8 mm. wide, double-folded, margins slightly thickened, densely but finely serrate, particularly towards the tapered tip; base of lf neither sheathing nor enlarged but marked by a purplish ligule. Infl. of 6–8 us. simple, light brown spikes; uppermost 2–4 spikes male, shorter and more slender than the female, sessile, ± approximate; remaining spikes female with a few male fls at the top, 3–7.5 × 1–1.5 cm., erect on stout peduncles, both spikes and peduncles becoming progressively shorter higher up the infl.; subtending bracts lfy, > infl., almost enclosing the peduncles with their sheaths. Glumes much > utricles, linear-lanceolate, emarginate or entire, faintly nerved, membr., light brown to dark brown or red-purple, paler towards the margins, midrib pale brown produced to a long hispid awn. Utricles 3–4.5 × c. 2 mm., unequally biconvex, obovoid, turgid, pale green or brownish green, lateral nerves well-marked, otherwise smooth, margins glab., abruptly contracted to a narrow, deeply bidentate beak slightly > 0.5 mm. long, orifice slightly scabrid; stipe c. 0.5 mm. long, whitish. Stigmas 3. Nut c. 2 mm. long, trigonous, oblong-obovoid, pale grey-brown.
DIST.: Ch.
In open peaty and swampy ground.
Four wide-lvd spp. of Carex have been recorded from the Chatham Is. In C. chathamica and C. trifida the female spikes are us. > 1 cm. diam. while they are narrower in C. ventosa and C. ternaria. C. chathamica may be distinguished from C. trifida by being us. a smaller plant and by the few-nerved minutely stipitate utricles; from C. ternaria it differs in having solitary, not geminate basal spikes.
C. chathamica differs from C. ventosa in having darker glumes > utricles, while glumes of C. ventosa are ± = utricles; the utricles of C. chathamica are also less distinctly nerved and beaked than those of C. ventosa. C. chathamica is a smaller plant of open peaty and swampy places while C. ventosa occurs in well-drained situations.
