Flora of New Zealand Series

Japanese cudweed

Annual, without stolons; stems 1-few, ascending to erect, simple or much- branched in lower 1/2, (1)-3-50 cm tall. Lvs all cauline at flowering, apetiolate, densely white-tomentose on lower surface, becoming sparsely tomentose to ± glabrous on upper, plane, usually spathulate to oblanceolate, sometimes elliptic or almost linear, cuneate, usually acute, rarely obtuse, mucronate, (6)-15-70-(100) × 2-10-(15) mm. Capitula c. 1 mm diam., numerous in dense globular terminal clusters, very rarely few axillary clusters below; longest subtending lvs c. 1-3× diam. of cluster. Involucral bracts narrow-oblong, gradually tapered to a blunt apex, 3.5-4.5 mm long; stereome green; lamina clear to pale or dark brown; gap and margins clear or tinged reddish purple. Achenes minutely papillate, 0.7-0.8 mm long.

N.; S.; K.: throughout up to c. 600 m but less common in southern South Id.

Also indigenous from Japan and Hawaii to S.E. Asia and Australia.

Coastal sites, waste places (especially stony areas), depleted grassland, gardens, forest margins, scrubland.

This sp. varies greatly in size and habit, but is easily distinguished by the small capitula clustered in dense globose heads, and by being annual. It is further distinguished from related indigenous gnaphaliums in having only 1 ⚥ floret per capitulum, and characteristically has distinctly undulate lf margins. Allan (1961) included this entity within his circumscription of G. involucratum, and references to G. japonicum Thunb. naturalised in N.Z. are mostly based on specimens of G. sphaericum.