2. Acaena novae-zelandiae Kirk, Trans. & Proc. New Zealand Inst. 3: 177. 1871.
Plants creeping or stoloniferous. Stems to 15 dm, 1.5–2 mm diam.; branches erect, ˂short˃, leafy. Leaves: stipules 3–5-fid; petiole 0.3–1 cm; blade 2–11 cm, leaflets 4–7 per side, bright shining green, oblong or elliptic, 4–17 mm, margins crenate-dentate, teeth 8–15, ˂smooth adaxially˃, abaxial surface glaucescent, usually pilose on veins and margins, adaxial sparsely pilose. Scapes axillary, 10–15 cm, 1–2 mm diam., ˂smooth˃, lacking both cauline leaves and multicelled hairs. Inflorescences 80–100-flowered, globose heads (9 mm diam. in flower, 20–35 mm diam. in fruit); bracteoles linear, pilose. Flowers 3.5 mm diam.; sepals 4, triangular, 1.5 mm, abaxially pilose, adaxially glabrous; stamens 2(or 3), filaments 1.5–2 mm, anthers white; stigma white, fimbriate. Fruiting hypanthia obtriangular, 3.5–5 mm diam., surfaces sericeous, 4-angled, each angle with a slender spine at apex, ˂red, sometimes lemon yellow˃, 7–12 mm, spines with 4–10 translucent, retrorse barbs 0.5 mm at apex, ˂surfaces glabrous˃. 2n = 42 (New Zealand).
Flowering May–Jun. Roadsides and paths, forest edges, logged lands, lawns, among cultivated ground covers and waste grounds; 0–200 m; introduced; Calif., Oreg.; Pacific Islands (New Guinea, New Zealand); Australia; also introduced in Europe (England, Ireland).
Herbarium records of Acaena novae-zelandiae are from the coastal ranges in California, Humboldt and Sonoma counties, around San Francisco and Monterey, and in Oregon.
Acaena novae-zelandiae has noxious weed status in the United States. The name A. anserinifolia (J. R. Forster & G. Forster) Druce was misapplied to A. novae-zelandiae by P. A. Munz (1968), this being the first published record of the taxon from North America.