Acaena emittens

Detailed description

Slender suffruticose perennial with dark brown subterranean stems < 2 mm diam. Stems prostrate and < 500 mm long or erect and < 50 mm long, c.0.7 mm diameter, brown, hirsute, epidermis flaking with age; internodes < 35 mm long on prostrate stems. Leaves hairy; stipules 2-6 mm long, margins, tips and undersides hairy, free portion linear, entire or bifid, < sheath; leaflets 3 or 4 pairs, the distal leaflet and 2 upper pairs obovate to suborbicular in outline, truncate at apex, shallowly cuneate at base, 2-10 × 2-6 mm; upper surface dull green, glabrous, smooth, with secondary venation indistinct; lower surface pale, glaucescent, the veins with appressed hairs; teeth 7-9 with margins thickened and recurved, hydathodes pink. Basal leaflet pairs less than ½ the size of the penultimate pair, or linear and smaller than stipule lobes. Hairs simple, unicellular, < 1.5 mm long, on stipules, rachis and leaflets. Inflorescence scape terminal on short shoots, 40-130 mm long at flowering, hardly elongating as fruit matures, c.0.5 mm diameter, moderately hairy, pale brown. Scape bract linear or foliose, occasionally subtending a single floret. Capitulum 4-6 mm diameter at flowering, 10-15 mm diameter (including spines) at fruiting. Bracteoles on receptacle linear, c. 3 mm long, with hairy margins. Florets c. 40-50, minutely stipitate. Hypanthium c.1 mm long, enclosing perigynous ovary, densely hairy, bearing 4 barbed spines which reach above the hypanthium rim. Sepals 4, arising from hypanthium rim, shortly joined at base, c. 1.5 mm long, elliptic, narrowed and thickened at tip, sparsely hairy on underside. Petals 0. Stamens 2; filaments unequal, up to 2 mm long; anthers 0.3 x 0.5 mm, white. Style 1, 1.5 mm long, including white, fimbriate stigma 0.6 mm broad and protruding from aperture of hypanthium. Fruit indehiscent with a single achene enclosed in the hypanthium, obconic, c.2.0 × 1.2 mm, brown, moderately hairy, 4-ribbed; spines 1 per rib, slender, 4-6 mm long, pale rose or brown, bearing a single rank of translucent, retrorse barbs at tip.