Flora of New Zealand Series

limestone wheatgrass

; Holotype: CHR 468517a! B. P. J. Molloy & K. W. Ryan L2 Marlborough, Leatham River, near limestone quarry, 600 m, 29 Jan. 1991.

Slender, flat-leaved, extravaginally branching, stoloniferous, tuft-forming perennial with rough patent spikelets on a short inflorescence. Leaf-sheath 2.5-5 cm, glabrous or retrorsely short hairy, thin, becoming fibrous below, sometimes reddened, margin hyaline. Auricles 0.1-0.5 mm, glabrous, barely clasping. Ligule 0.6-1.25 mm, lacerate. Collar dark brown or purpled, glabrous. Leaf-blade 6-25 cm × 0.5-3.5 mm, soft, flat, thin, adaxially ribs hirsute or minutely scabrid; margins smooth below, prickle-teeth above; abaxially with conspicuous white midrib and 2 white lateral ribs, evident prickle-teeth on ribs above. Culm 17-60 cm, slender, geniculate and decumbent below; nodes conspicuous, swollen, dark brown or almost black; internodes glabrous or antrorsely lanate immediately below inflorescence. Inflorescence a spike-like raceme 3-13 cm, subtended by a small hair-fringed bract; spikelets 4-13, imbricate; rachis internodes short, sulcate, antrorsely toothed on margins, elsewhere antrorsely lanate or glabrous. Spikelets 10-14 mm, of 4-6 florets on short (0.3 mm) hairy pedicels, broadside to tough rachis, becoming patent. Glumes unequal, narrowly or broadly triangular-acute, < spikelet, nerves 3-5, evident white, keels eccentric, abaxially irregularly prickle-toothed, adaxially clothed in short white stiff antrorse hairs, margin very narrowly chartaceous, toothed; lower 2.5-4 mm, upper 3.7-5.5 mm. Lemma 9-11 mm, indefinite canaliculate awn 1.5-4 mm, 5-nerved, keel obscure below, abaxially with abundant antrorse, ± appressed prickle-teeth, margin very narrowly chartaceous, toothed. Palea 5.3-7 mm; keels shortly denticulate; apex shallowly bifid, ciliate; interkeel with abundant short, white, stiff, antrorse hairs; flanks with short hairs at apex and along margin. Callus 0.25-0.4 mm, surrounded adaxially by short stiff hairs; disarticulation oblique. Rachilla 1.0-1.25 mm, with stiff appressed white hairs. Lodicules 0.4-0.6 mm, ciliate. Anthers 2.4-2.75 mm. Gynoecium: ovary 0.8-1 mm; stigma-styles 1.75-2 mm. Caryopsis 3.5-4 mm, linear; embryo 0.75 mm; hilum linear, 3.5-3.75 mm. 2 n = 14.

Endemic.

The species is currently known from three areas: (1) inland Marlborough, Leatham River, (2) inland North Canterbury between Whitewater and Flock Hill streams, and (3) coastal North Canterbury at Mt Cass, and appears to be confined to limestone habitats. The ecology and conservation of A. calcis are described by Molloy, B. P. J. N.Z. J. Bot. 32: 37-51 (1994). It is a self-compatible and chasmogamous species.