Flora of New Zealand Series

Sisymbrium islandicum Oeder Fl. dan. Ic. 3, 1768, t. 409.

Nasturtium palustre DC. Syst. 2, 1821, 191.

N. sylvestre A. Rich. Essai Fl. N.Z. 1832, 309

nonR. sylvestris (L.) Besser Enum. Pl. Volh. 1822, 27.

Annual erect or spreading ± pilose herb up to 30 cm. tall, with rather stout taproot; main stem and branches ± quadrangular in section; branches at very wide angle to stem, terminating in lax racemes. Basal lvs up to 10 cm. long, on petioles ± 1 cm. long, ± ovate-oblong in outline, sublyrately pinnate to pinnatisect. Pinnae up to 1·5 cm. long, coarsely dentate-serrate; terminal lflts up to 2.5 cm. long, ovate to narrow- ovate, acute to acuminate; lowest lflts minute. Cauline lvs similar, smaller, us. ∞.Racemes up to 5 cm. long at anthesis, elongating to ± 10 cm. in fr. Fls small, rather distant, subopp. to alt. on slender sub- patent petioles ± 5 mm. long. Sepals 1·5-2 mm. long; petals obovate- spathulate, 1·5-2 mm. long. Median honey glands developed. Siliques or silicles ellipsoid, ± 5-7 × 2 mm.; valves convex; styles stiff, hardly 1 mm. long, stigma hardly wider. Seeds many, ± oval in outline, very finely papillose, c. 0·5 mm. diam., reddish brown.

DIST.: N., S. Occ. to frequent throughout in lowland to montane riverine areas and damp ground.

FL.- FT. 11-3.

The description is drawn up from plants of montane riverbeds. I am not at all sure that our sp. is properly placed under R. islandica. How far the more luxuriant, glabrate forms of other areas with petals up to 4 mm. long are indigenous or naturalized is uncertain.