Citation: Airy Shaw, Kew Bull. 35:683 (1980).

Synonymy: Synostemon rigens F. Muell., Fragrn. Phyt. Aust. 2:153 (1861); Phyllanthus rigens (F. Muell.)Muell.-Arg., Flora 47:513 (1864); Glochidion rigens (F. Muell.)H. Eichler, Suppl. 210 (1965).

Common name: Stiffspurge.

Description:
Rigid twiggy shrublet, stems terete, rigid, to 100 rarely 150 cm long, the branchlets often ending in a spine, minutely hispidulous; leaves on almost obsolete petioles, 1 to few-fascicled, on very short dark nodule-like spurs, lamina shortly cuneate-obcordate or obovate-cuneate, 1-3 x 2-3 rarely to 8 mm long, more or less conduplicate, minutely hispidulous; stipules triangular-subulate, densely crowded with short scales forming when dry a black-purple nodule; monoecious.

Flowers solitary at each nodule, apetalous; male flowers sessile, calyx funnel-shaped, 2-3 mm long, segments united in a ribbed tubular calyx, minutely papillose-hispidulous, with short ovate lobes less than 0.5 mm long, acute, erect; filaments and anthers connate; female flowers on peduncles as long as or longer than the leaves, calyx segments free or shortly connate, oblong-spathulate, c. 3 x 1 mm, subobtuse, minutely papillose-hispidulous externally, persistent in fruit; ovary trigonous, c. 1 mm long, glabrous, attenuated into a stout trigonous style c. 1 mm long, bearing 3 small minutely capitate stigmas.

Capsule subglobose, 5-7 mm diam., slightly 6-ribbed, greenish-brown, reticulate-pitted, drooping; seed incurved, c. 5 mm long, whitish, strongly reticulate-wrinkled on the back, less so on the sides.

	Sauropus rigens twig, leaf, female flower, fruit and seed.
Image source: fig 411b in Jessop J.P. & Toelken H.R. (Ed.) 1986. Flora of South Australia (4th edn).

Published illustration: Airy Shaw in Jessop (1981) Flora of central Australia, fig. 219 as Synostemon; Cunningham et al. (1982) Plants of western New South Wales, p. 462 as Phyllanthus rigens.

Distribution:  Occurring as isolated bushes, rarely in small groups in mallee communities, in calcareous red earths or shallow stony soils along hill escarpments.   N.T.; N.S.W. Conservation status: native Flowering time: May — Oct.

SA Distribution Map based on current data relating to specimens held in the State Herbarium of South Australia

Biology: A spiny-looking plant, often sparsely covered with small leaves, apparently ungrazed by stock.

Author: Not yet available