Acaena tesca

Detailed description

Low-growing or mat-forming suffruticose perennial, with dark brown subterranean stems up to 2.5 mm diameter. Long shoots prostrate, rooting at nodes, c.10 cm long with internodes c.10 mm long; short shoots erect, c.20 mm long, c.1 mm diameter, pale brown, sparsely hairy. Leaves imbricate on short shoots, imparipinnate, 10-50 × 5-10 mm. Stipules 3-4 mm long, with margins and tips hairy, and free portion c.1 mm long, entire, triangular. Leaflets 3-5 pairs, gradually reduced in size to base of rachis, broad obovate or orbicular in outline, 2.5-5.0 × 2.5-4.0 mm, truncate at apex or slightly emarginate; upper surface glaucous, with sparse to moderately dense appressed hairs, and indistinct veins; lower surface glaucous, with appressed hairs on veins; teeth 6-9, dull red with pink hydathode area at tip, weakly penicillate. Hair simple, unicellular, 0.2-0.8 mm long, on stipules, rachis and leaflets. Capitulum terminating short shoot, sessile, subtended by several leafy bracts, 5-8 mm diameter at flowering, 25-35 mm diameter (including spines) at fruiting. Bracteoles on receptacle linear-lanceolate, c.2 mm long, with hairy margins. Florets c. 10, very shortly stipitate. Hypanthium c.1.5 × 1.5 mm, enclosing perigynous ovary, sparsely hairy, with 4 very short spines inserted third-way from apex. Sepals 4, arising from hypanthium rim, free or shortly joined at base, 1.5 mm long, ovate, thickened at tip, hairy below. Petals 0. Stamens 2-3; filaments up to 2.5 mm long; anthers 0.5 × 0.6 mm, white. Styles 2, 2.5 mm long including stigma; stigma white, fimbriate, 1 mm broad, protruding from aperture of hypanthium. Fruit indehiscent; achenes 2, enclosed in the hypanthium; hypanthium turbinate, c.2.5 × 2.0 mm, red-brown, 4-ribbed, sparsely hairy; spines 4, 5-20 mm long, red, softly sparsely hairy, at least when young, with a group of retrorse hairs at tip.