Argemone albiflora Hornem.
Family - Papaveraceae
Stems - From a massive woody taproot, erect, herbaceous but stout, to +1m tall, single or multiple from the base, terete, glaucous, with a moderate number of needle-like prickles, with yellow latex sap, simple below, branching in the apical 1/2.
Leaves - Alternate, sessile, auriculate, pinnately lobed, to +/-15cm long, +/-7cm broad, reduced upward, oblanceolate in outline. Lobes (opposing) generally as long as the solid portion of leaf tissue between them, to 3cm long, 2cm broad, with straight prickles (to 3mm long) on the coarse teeth of the margins. Straight prickles on the veins of the leaf abaxially. Veins of the leaf greatly expressed below. Leaf tissue generally glabrous, dull green adaxially, lighter below. Auricles rounded, partially enclosing the stem, with prickles.
Inflorescence - Cymose arrangement of large showy flowers from the upper leaf axils. Each division of the inflorescence subtended by a reduced leaf (bract). Pedicels 5-10cm long, glaucous, with a few prickles.
Flowers - Petals 6, white, distinct, obtriangular, to 6cm broad, +4cm long, glabrous, yellowish at the base, with the apical margin fringed or crenulate. Stamens many (+100), from below the pistil, ascending. Filaments yellow, clavate, glabrous. Anthers falcate, basifixed, 3-4mm long, .6mm broad, longitudinally dehiscing. Ovary 8mm long, 4mm broad in flower, ovoid, quickly enlarging, with dense antrorse prickles, unilocular. Placentation parietal. Stigma capitate, maroon, 4mm broad. Style absent. Sepals caducous. Fruit to 4cm long, -2cm broad, 5-ridged, bluish-green, with many antrorse prickles, with many seeds. Seeds tuberculate, globose, 2-2.5mm in diameter, with an obvious caruncle.
Pistil close-up. Petals and stamens removed.
Flowering - May - September.
Habitat - Waste ground, roadsides, railroads.
Origin - Native to U.S.
Other info. - This striking species can be found in a handful of Missouri counties. It is easily recognized by its large white flowers and prickly stems, leaves, and fruits. A similar species, A. mexicana is practically identical but has bright yellow flowers. This latter species can be found in the Yellow Flowers Alternate Leaves section of this website.
Photographs taken of Hwy W, Ripley County, MO., 6-5-04.