Flora of New Zealand Series

scentless mayweed

Almost scentless, annual or biennial herb sometimes regrowing from old rootstock. Stems erect or ascending, 15-100 cm tall, ribbed, usually glabrous, sometimes sparsely hairy, branched only above to form infl. or sometimes also much-branched from base. Basal and lower cauline lvs appearing shortly petiolate, but usually with very reduced leaflets along sheath, usually narrow-obovate, sometimes ovate, glabrous, mostly 3-pinnatisect, 15-150 × 10-60 mm; ultimate segments filiform, entire, not all in one plane giving a feathery appearance; cauline lvs similar to basal, but apetiolate and above becoming smaller and with fewer segments. Corymb diffuse, of few to many capitula. Involucral bracts glabrous or with a few scattered hairs, 4-7 mm long; margins pale or dark brown, membranous. Capitula c. 30-50 mm diam.; ray florets 12-numerous; ligules white; disc florets numerous, yellow. Achenes 1.7-2.5 mm long, brown, narrow-obpyramidal to cylindric; inner surface with 3 thick ribs; outer surface rugose, with 2, ± globose or slightly elongated glands at apex; corona crenulate, c. 0.1 mm long.

N.: Auckland City, Wellington City, Hutt Valley; S.: mainly dry eastern areas from Marlborough to C. Otago and Southland.

Mediterranean to W. Asia and S. Russia 1870

Waste places, especially roadsides, coastal areas, and stony grassland.

FL (Aug)-Jan-Feb-(May).

The achenes (Fig. 17) distinguish T. inodorum from all other naturalised N.Z. Anthemideae. Scentless mayweed, or scentless chamomile as it is sometimes called, is often abundant on roadsides and in waste places (Plate 1). It has previously been known in N.Z. as T. maritimum, Matricaria perforata, M. inodora, and Chrysanthemum inodorum.