Flora of New Zealand Series

small-leaved wireweed

Glabrous annual, prostrate or decumbent, often forming dense leafy mats; stems to c. 70 cm long; taproot fairly stout. Lvs of young and main stems similar or slightly > those of branches, subsessile or very shortly petiolate. Lamina 7-15 × 2-6 mm, narrow-elliptic to elliptic or elliptic-oblong, sometimes broader in very small-leaved plants, green, entire; lateral veins evident beneath; base cuneate to rounded; apex obtuse to subacute; apical branch lvs sometimes < 5 mm long. Ochreae initially 2-4 mm long, silvery-hyaline, ± acute, often tinged pink, becoming brown and lacerate. Fls 1-3-(6) in fascicles, extending almost to base of plant; pedicels short, enclosed by ochreae. Perianth 2-3 mm long, usually united at anthesis for ?-1/2 length; segments imbricate, ± oblong, glabrous, accrescent; margins and apex generally white, sometimes rose. Nut 1.7-2.5 mm long, generally ovoid but ranging from ± biconvex to ± trigonous, dark reddish brown, granular but ± shining, enclosed in perianth.

N.; S.: common.

Europe 1940

Cultivated ground, waste places, depleted pastures, riverbeds, roadsides.

FL Nov-Jun.

P. arenastrum and P. aviculare have been treated as 1 sp. in the past but are now usually considered distinct. They often grow together, but P. arenastrum is apparently less abundant than P. aviculare. P. arenastrum is best distinguished from P. aviculare by the much more densely leafy stems with generally smaller and blunter lvs which vary little in size from branches to lower main stems. The degree of fusion of the perianth and the nut shape are also important when considered together; of less significance is the greater prominence of the ochreae which is the result of the shorter internodes in P. arenastrum. P. arenastrum has previously been known in N.Z. as P. aequale.