1. P. anserina, Linn. Sp. Plant. 495.—Rootstock tufted, giving off long creeping runners rooting at the nodes. Leaves all radical, numerous, 2–6 in. long, unequally pinnate, green and glabrous or slightly silky above, white with appressed silvery tomentum beneath; leaflets numerous, ⅓–1 in. long, oblong or obovate or rounded, alternate ones often minute, deeply and sharply toothed or incised. Peduncles from the rootstock or rooting nodes, 2–6 in. long, 1-flowered. Flowers ½–1 in. diam., yellow. Calyx silky and villous; lobes lanceolate or oblong; bracteoles lobed and cut. Petals obovate. Achenes glabrous or nearly so; receptacle villous.—Hook. f. Fl. Nov. Zel. i. 54; Handb. N.Z. Fl. 54; Kirk, Students Fl. 131.
Var. b, anserinoides.—Leaflets smaller, ¼–½ in. long, sessile or petioled.—P. anserinoides, Raoul, Choix, 28.
North and South Islands, Chatham Islands: Common in moist places from the Auckland Isthmus southwards, ascending to nearly 3000 ft. Silver-weed. December–January.
The typical form of the species is almost cosmopolitan; the var. anserinoides, which is often difficult to distinguish from it, is said to be endemic. It is much the most plentiful state in New Zealand.
4. ACÆNA, Linn.
Silky or glabrous perennial herbs; stems erect at the tips, decumbent or creeping at the base, or altogether prostrate. Leaves alternate, unequally pinnate; leaflets toothed or incised; stipules sheathing at the base, adnate to the petiole. Flowers hermaphrodite or unisexual, small, crowded in a terminal globose head, or in an interrupted spike. Calyx-tube persistent, obconic or turbinate or campanulate, constricted at the mouth, terete or angled, naked or at length armed with simple or barbed spines; lobes 3–7, valvate, persistent or deciduous. Petals wanting. Stamens 1–10, very rarely more. Carpels 1–2, wholly immersed in the calyx-tube; style subterminal, short, exserted, dilated into a fimbriate or plumose stigma; ovule solitary, pendulous. Achenes solitary or rarely 2, enclosed in the hardened calyx, which is usually armed with subulate spines or bristles. Pericarp bony or membranous.
Species about 35, widely spread in the temperate regions of the Southern Hemisphere, but most plentiful in Chili and Peru. One of the New Zealand species is found in Australia and Tasmania, and another in Fuegia and the Falkland Islands; the remainder are all endemic.
| A. Calyx-tube not compressed, 4-angled, usually with a stout spine at each angle, rarely spineless. | |
| * Calyx-tube longer than broad. | |
| Usually silky. Heads large, ¾–1¼ in.; spines long, red-purple. Achene narrowed at both ends | 1. A. novæ-zealandiæ. |
| Usually silky. Heads ½–¾ in. Achenes broadest near the base, narrowed upwards | 2. A. sanguisorbæ. |
| Usually glabrous; leaves often glaucous. Heads ½–¾ in. Achenes narrowed at both ends | 3. A. adscendens. |
