Greek dis - two, oon - egg; referring to the paired seeds (also found in many other cycads).

Trunk generally unbranched, sometimes ovoid, covered with persistent old leaf bases. Leaves numerous. Leaflets attached towards the edge of the leaf midrib, not or hardly narrowing at the base which fuses with and extends down the midrib (decurrent) at the point of attachment, those at the base of the frond shorter, with a prickly tip and sometimes with marginal spines. Cones more or less stalkless; scales spirally arranged. Male cones cylindrical, hairy. Female cones ovoid; ovules hairy and on short stalks; seeds round in section with cream-coloured coat.

Cultivated in warmer areas, mostly New South Wales and Queensland. The seeds are poisonous unless cooked.

10 species (9 in Mexico, 1 in Honduras).

Leaflets not or hardly narrowed at the base; cone scales pointed but without any spines, projections or extended flat faces.

Griffiths (1988).

Source: Spencer, R. (1995). Zamiaceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 1, Ferns, conifers & their allies. The identification of garden and cultivated plants. University of New South Wales Press.