Flora of New Zealand Series

pink-head knotweed

Mat-like perennial with rather slender, ± woody rootstock and long, slender, creeping, rooting stems; shoots grooved, ± brown-hairy, reddish. Lvs on all shoots similar; petiole short or lvs subsessile. Lamina 15-40-(55) × 8-25-(35) mm, ± broad-ovate, becoming red with age, rose-pink and with brown or white hairs on veins below and generally on the midrib above, with a crescent-shaped brown or purplish mark above; margins entire or nearly so, strongly ciliate and with red marginal line; base ± cuneate, slightly oblique; apex acute or subacute. Ochreae (2)-3-9 mm long, brown-hairy, truncate. Fls in globose or subglobose heads, numerous; head (5)-7-15-(20) mm diam.; peduncles usually > lvs, erect, with 1-6 branches in the upper 1/2, glandular-hairy; pedicels 0; bracts scarious, almost = fls. Perianth 2.5-3 mm long, pink, scarcely accrescent; segments imbricate, ovate or elliptic-ovate, glabrous. Nut c. 1.5 mm long, trigonous, dark brown, smooth and glossy, tightly enclosed in persistent perianth.

N.: warmer, usually coastal areas; S.: around Nelson, Westport, occasional down the E. coast as far as Banks Peninsula.

Warm temperate Himalaya 1958

Cultivation escape, steep banks, crevices of walls and amongst rocks near habitations, also less modified habitats such as coastal cliffs.

FL Jan-Dec.

In areas experiencing little or no frost P. capitatum is often a nuisance within gardens because of its invasive habit, although it rarely grows in well-cultivated ground. It is very easily recognised by its creeping habit, broad lvs and globular heads of pink fls with purple, ± exserted anthers.