Citation: F. Muell., J. Trans. Vict. Inst. 2:77 (1858).

Derivation: Greek osteon, bone; karpos, fruit; alluding to the hard fruiting perianth.

Synonymy: Not Applicable

Common name: None

Description:
Erect perennial herbs branching from the base, usually glabrous except for axillary pubescence; leaves alternate, succulent, subterete to clavate, 6-10 mm long.

Flowers bisexual, solitary, axillary, glabrous apart from the ciliate margin to the lobes; perianth tube somewhat fleshy; upper perianth membranous, 5-lobed; stamens 5.

Fruiting perianth glabrous; tube woody, subglobular, straw-coloured when dry; limb hidden in the sunken apex of the tube; radicular (opposite the radicle) tubercle prominent, either bare or bearing an erect wing; inter-segment tubercles 0-4 or replaced by vertical wings; style short and hard, pubescent at the apex; seed horizontal, with a horizontal to ascending or erect radicle.

Distribution:  5 species endemic to temperate Australia.

Biology: No text

Key to Species:

1. Fruiting perianth stipitate on a hollow base or, if sessile, then with 5 erect wings
2. Vertical wings absent; radicular tubercle prominent; inter-segment tubercle 0 or 1	O. acropterum 1.
2. Vertical wings present
3. Vertical wings 1-3
4. Vertical wings 1 or 2, obovate, not extending downward along the tube	O. acropterum 1.
4. Vertical wings 2 or 3, semicircular	O. dipterocarpum 2.
3. Vertical wings 5	O. pentapterum 3.
1. Fruiting perianth subglobular, sessile or almost so, without wings	O. salsuginosum 4.

Author: Not yet available