Gard. Chron., ser. 3, 78: 433. 1925.
Herbs, perennial or biennial, usually short-lived, succulent, glabrous. Roots fibrous or tuberous. Stems: flowering shoots annual, prostrate to ascending. Leaves rosulate, or cauline and alternate or opposite, sessile; stipules absent; blade linear, ± grooved, ± triangular in cross-section. Inflorescences axillary, flowers solitary; peduncle erect, 10 (–12) cm; bracts absent. Flowers showy, tubular, 5–13 cm diam.; calyx lobes 5, green, unequal, wider at base, apex cylindric, basal margins of inner 3 lobes papery; petals (including petaloid staminodia) 250, distinct, free, yellow; nectary present; stamens 500+, distinct; filament bases hairy; pistil 10–25-carpellate; ovary inferior, connate in proximal 1/2, 10–25-loculed; placentation parietal with 2 seed pockets on outer wall of each locule; styles absent; stigmas 10–25, filiform. Fruits capsules, conic; valves 10–25, opening but not spreading when moistened, finally separating into 10–25 segments. Seeds 75–200, spheric, margins keeled, smooth; arils absent.
Species 10 (1 in the flora).
According to G. D. Rowley (1978), “Conicosia capsules open once only on wetting and do not close again. The loose seeds are then shaken out over a period of time as from a pepper pot. Subsequently the light, buoyant capsule breaks off and rolls along the ground, scattering further seeds over greater distances. Finally it decomposes into segments, each composed of a winglike membrane that divided the cell chambers. In this are two tiny pouches, each trapping a single seed. These seeds have a long viability (I have had good germination after five years) and so they ensure perpetuation in time as well as space. Three different dispersal mechanisms from one fruit must constitute something of a record; indeed, the fruits of Mesembryanthemaceae are among the most complicated structurally of any plant.” The two tiny pouches referred to by Rowley often contain multiple seeds, one to three or none per pouch (pers. obs.). See G. Schwantes (1957) for a description and illustration of the pockets, as shown in Conicosia brevicaulis.
Herrea Schwantes is closely related to Conicosia; it has been wrongly cited for California. Conicosia and Herrea share a number of characteristics; they are distinguished by the dissepiments (partitions) of the fruits, which reach to the apex of the valves in Herrea and halfway up the valves in Conicosia. In Herrea, the capsule splits into many segments without a firm central column; in Conicosia, the capsule does not separate into many segments, or at least not until decaying away. Herrea is included in Conicosia by H. D. Ihlenfeldt and M. Gerbaulet (1990). In general, conicosias do well in poor, sandy soils (U. Van der Spuy 1971). They grow readily and naturalize in sandy dune habitats in coastal California.