Flora of New Zealand Series

≡Diplax avenacea Raoul, Ann. Sci. Nat. Ser. 3, Bot. 2: 116 (1844)

≡Microlaena avenacea (Raoul) Hook.f. var. avenacea (autonym Zotov 1943 op. cit. p. 235)

≡Ehrharta diplax F.Muell., Fragm. 7: 90 (1870); 

Holotype: P! Raoul Akaroa in umbrosis.

bush rice grass

Caespitose wide-leaved perennial from short rhizome with long culms and large inflorescences. Branching extravaginal, occasionally with stolons rooting at nodes; cataphylls broad and shining. Leaf-sheath smooth or sometimes scabrid; keel stout, often prickled towards apex. Ligule to 0.5 mm, membranous, crenate or shallowly toothed, broadly triangular, ciliolate. Auricle 1, ± 5 mm, margin hairs 2-4 mm. Leaf-blade to 50 cm × 6-12 mm wide, bright green, keel strong, sometimes scabrid below; sharp, fine, close-set, dense antrorse prickles on margins above becoming smooth below except for auricle hairs extending for c. 1 cm; abaxially rough occasionally scabrid, occasional prickle-teeth near ligule. Culm to 1.25 m; internodes laterally compressed and conspicuously, longitudinally grooved, smooth to finely prickle-toothed. Panicle 25-65 cm, nodes widely spaced, branches filiform, > internodes; nodes with short branches of close-set spikelets and long flexuous branches to 20 cm, naked below; rachis longitudinally grooved, finely scabrid to ± smooth, branches and pedicels finely prickle-toothed. Spikelets 18-30 mm, solitary, on short or long pedicels. Glumes unequal, 1-nerved occasionally 3-nerved, margins ciliate, entire or 2 or 3-toothed especially upper; lower to 1 mm, = callus hairs, upper 1-2.5 mm > callus hairs. Lower Ø lemma 9-15-25 mm, 5-nerved, prickle-toothed especially on keel, adaxially hairy above, awn > ½ lemma length; callus hairs to 1 mm; upper Ø lemma 12-23-27 mm, 3-nerved, scabrid above, awn > ½ lemma length; callus hairs 1-2 mm. ⚥ lemma 5-7-12 mm, 3-nerved, awnless and ciliate or occasionally shortly (0.5-2 mm) awned from bifid apex; callus hairs few and short. Palea 3-4-5 mm, membranous, acute, upper margins and apex ciliate. Lodicules 2, 0.6-1.2 mm, > ovary, lobed occasionally flabellate, truncate and finely erose, occasionally lobes long hairy, persistent or falling with caryopsis. Stamens (1)-2, anthers (1)-2-3-(4) mm. Gynoecium: ovary 1 mm; stigma-styles 1-1.5-2.5 mm, styles naked below. Caryopsis 2-3.5-5 mm, often falling free; embryo 0.5-0.7 mm. 2 n = 48. Fig. 2. Plate 6C.

N.: throughout; S.: Nelson and west of Main Divide to Fiordland, less frequent in east; St.; A. Forests; sea level to 1300 m.

Indigenous.

Willemse, L. P. M. Blumea 28: 181-194 (1982) treated New Zealand, Fijian and Tahitian plants as Ehrharta diplax var. diplax, and those of New Guinea and Irian Jaya as var. giulianettii (Stapf) L.P.M.Willemse. The autonym M. avenacea var. avenacea was generated by Zotov, V. D. T.R.S.N.Z. 73: 235 (1943); the need for it does not arise here as varietal rank is not used.

Fig. 2 Microlaena avenacea S, spikelet, × 9; G 1, G 2, glumes, × 9; L 1, L 2, lemma of Ø florets, × 9, L 3, lemma of ⚥ floret, × 9; P, palea dorsal view, × 9; Lo, lodicules, × 24; O, ovary, styles and stigmas, × 24; St, stamens, × 24. © All rights reserved. [Image: 4X7N]