Cyclospermum Lag.
Glabrous, annual herbs. Lvs 1-4-pinnate; segments narrow. Umbels simple or compound, sessile, lf-opposed; bracts and bracteoles 0. Petals white, regular, with entire, acute, inflexed apex; calyx teeth 0. Fr. ovoid-oblong, slightly flattened laterally, not beaked, spineless but sometimes setose; commissure narrow; ribs 5 per mericarp, equal, stout; vittae solitary in furrows.
c. 4 spp., America, Australia. Naturalised sp. 1.
Often included within Apium, this small group of annuals differs in cotyledon characters, pollen morphology [Cerceau-Larrival, M.-T., Bull. Soc. Bot. France 3 : 93-96 (1964)] and chromosome number (Apium n = 11, Ciclospermum n = 7).
