Argemone albiflora Hornem.

White Prickly Poppy

Family - Papaveraceae

Habit - Taprooted annual or biennial forb.

Stems - Ascending to erect, herbaceous but stout, to 1 m, single or multiple from the base, branching in the upper half, terete, glaucous, with a moderate number of needle-like prickles, with yellow sap.

Argemone albiflora stemStem and leaf base.

Leaves - Basal and alternate on the stems, the stem leaves to 15 cm, progressively shorter toward the stem or branch tips, all sessile, the uppermost leaves usually with a pair of rounded auricles at the base, clasping the stem. Leaf blades moderately to deeply pinnately lobed with relatively broad, often U-shaped sinuses, the lobes variously shaped, with irregularly toothed margins, these armed with staw-colored, slender prickles, the surfaces glabrous or armed with scattered slender prickles along the main veins, glaucous. Veins of the leaf greatly expressed below. Leaf tissue generally glabrous, dull green adaxially, lighter below.

Argemone albiflora leavesLeaves.

Inflorescence - Cymose arrangement of large showy flowers from the upper leaf axils. Each division of the inflorescence subtended by a bract. Pedicels 5-10cm long, glaucous, with a few prickles.

Flowers - Petals 6, white, distinct, obtriangular, to 6 cm broad, 4 cm long, glabrous, yellowish at the base, with the apical margin fringed or crenulate. Stamens numerous, from below the pistil, ascending. Filaments yellow, glabrous. Anthers falcate, 3-4 mm long, 0.6 mm broad, dehiscing longitudinally. Ovary 8 mm long, 4 mm broad in flower, ovoid, enlarging, with dense antrorse prickles, unilocular. Placentation parietal. Stigma capitate, maroon, 4 mm broad. Style absent. Sepals caducous.

Argemone albiflora flowerCorolla.

Argemone albiflora pistilPistil close-up. Petals and stamens removed.

Fruits - to 2 cm long, narrowly ellipsoide, 5-ridged, bluish-green, prickly, many seeded. Seeds tuberculate, globose, 2-2.5 mm in diameter, with an obvious caruncle.

Argemone albiflora fruitFruit.

Flowering - May - September.

Habitat - Waste ground, roadsides, railroads.

Origin - Native to U.S.

Other info. - This striking species is uncommon in Missouri, being found in only a few counties. It is easily recognized by its large white flowers and prickly stems, leaves, and fruits. A similar species, A. mexicana is very similar but with bright yellow flowers. This latter species can be found in the Yellow Flowers Alternate Leaves section of this website. These and other members of the genus are common and showy sights along roadsides in the western and southwestern U.S. The plants are pretty but the foliage says, "Don't Touch!"

A. albiflora can be subdivided into ssp. albiflora and ssp. texana, based upon the shape of the fruits and their prickles.

Photographs taken of Hwy W, Ripley County, MO., 6-5-04.


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