Flora of New Zealand Series

Mercury Bay weed

Perennial herb, with most parts densely hairy; hairs white, ± appressed, forked. Stems stoloniferous, freely branching, purplish, forming extensive mats or low cushions to 5 cm high. Lf internodes 1-2 cm long; petioles erect or nearly so, to 6 cm long, short on very exposed stolons. Lamina (5)-10-30 mm diam., suborbicular to reniform, membranous, glabrous or nearly so and dull above, with appressed hairs below; veins raised beneath, not impressed above; base broad-cordate; apex rounded or slightly emarginate. Peduncles 5-15 mm long, bract very small and inconspicuous. Calyx c. 2 mm long, densely hairy outside; lobes alternately linear-oblong and ovate-oblong, obtuse to subacute. Corolla 4-5 mm diam., greenish white, lobed to c. 1/2 way; lobes narrow-oblong to lanceolate, = calyx lobes at anthesis, becoming > calyx lobes. Anthers violet or violet-margined. Ovary densely hairy. Capsule usually deeply 2-lobed, with 1-(2) seeds per loculus, 2-2.5 × 4-5 mm, more rarely only 1 locule developed, indehiscent, slightly to strongly hispid, > calyx. Fruiting calyx to 3 mm long, fruiting peduncle recurved. Seeds c. 1.5 mm long, yellow to dark brown.

N.: N. Auckland (Kawau Id) to Wellington; S.: Christchurch.

West Indies, S. North America 1978

Usually a lawn weed.

FL Sep-Feb.

D. micrantha has been widely planted as a lawn in warmer parts of N.Z. and in many places it has thrived and spread naturally to a limited extent. Until recently this plant has been referred to the indigenous D. repens, but Forde, M. B., New Zealand J. Bot. 16: 283-285 (1978), has shown that the lawn plant represents an introduced American element sometimes placed within a broad concept of D. repens but more correctly treated as the distinct sp. D. micrantha. Self-pollination occurs, but cleistogamy, which has been reported for D. micrantha elsewhere, has not been substantiated for N.Z. (Forde, loc. cit.).