Flora of New Zealand Series

nahui

Decumbent perennial herb with stems to c. 50 cm long, usually at least partly rooting at lower nodes, often much-branched and with a longitudinal row of hairs on 2 opposite sides. Lvs usually shortly petiolate, 1-4-(6) cm × 2-8 mm, linear to narrow-oblong, narrow-elliptic or oblanceolate (shape may vary on the one plant), glabrous or almost so, entire or obscurely denticulate; base attenuate; apex obtuse to subacute. Fls in dense, sessile, axillary, ± globular heads, 5-8-(10) mm diam. Bract and bracteoles much < perianth, white or pinkish white, scarious. Tepals unequal, 2-3 mm long, white, scarious, with soft apex; longer tepals linear-lanceolate or lanceolate, acuminate; shorter tepals ± ovate, ± acute. Fertile stamens 2-3; staminodes minute. Utricle ± 1.5 × 2 mm, light brown, strongly compressed laterally, broadly obcordate; margin thickened. Seed c. 1 mm diam., shining.

N.: local throughout but becoming uncommon towards the Wellington area; S.: known only from Birdling's Flat and Lake Forsyth area, Canterbury.

Old World tropics 1838

Usually in wet or damp places, sometimes in waste places in and around towns and cities on comparatively dry ground, occasionally a garden weed.

FL Dec-Feb.

Nahui is described as indigenous in N.Z. Floras but its habitats are always artificial or greatly modified. Thus, it may have been introduced by Polynesian settlers. It has almost certainly spread southwards in N.Z. during the past century, in part by dispersal of frs in mud on birds' feet. In the tropical Pacific it is also a plant of modified swamps, especially taro plantations, and may also be a human introduction.

The N.Z. plant has often been considered conspecific with the Australian A. denticulata R. Br., but on the basis of fr. characters as given by Black, J. M., Fl. S. Australia ed. 2 (1943), N.Z. material is better referred to the tropical Pacific A. sessilis. In lf shape, however, N.Z. material is more like A. denticulata than the broader-elliptic-leaved A. sessilis.