Argemone mexicana L.

Mexican Prickly Poppy

Argemone mexicana plant

Family - Papaveraceae

Habit - Taprooted annual or biennial forb.

Stems - Ascending to erect, herbaceous but stout, to 0.8 m, single or multiple from the base, branching in the upper half, terete, glaucous, sparsely prickly, with yellow sap.

Argemone mexicana stemStem.

Leaves - Basal and alternate on the stems, to 25 cm, the stem leaves progressively shorter toward the stem or branch tips, all sessile, at least 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, with irregularly toothed margins, these armed with staw-colored, slender prickles, the surfaces glabrous or with scattered slender prickles along the main veins, glaucous, with lighter mottling along the main veins.

Inflorescence - Flowers terminal, loose clusters or solitary flowers at the stem or branch tips, the flowers short- to long-stalked, the stalk erect or ascending at flowering, closely subtended by 1 or 2 reduced leaflike bracts, the receptacle slightly expanded at the tip.

Flowers - Sepals 3, free, the body 9-18 mm long, oblong elliptic, broadly pointed at the tip, sometimes prickly, also with a prominent, ascending, conic, dorsal horn near the tip. Petals 4, to 3.5 cm, broadly obovate, broadly rounded and often somewhat uneven or slightly ruffled at the tip, white to pale yellow or yellow. Stamens 20-50. Ovary lacking a well-differentiated style at flowering, the stigma more or less capitate, with 4-6, shallow, spreading lobes.

Argemone mexicana flower

Fruits - Capsules to 45 mm long, oblong to ellipsoid in outline, the surface unarmed or sparsely to moderately prickly.

Argemone mexicana fruitsAtypical fruit.

Argemone mexicana fruitTypical fruit.

Flowering - May - August.

Habitat - Rocky open ground, disturbed areas, roadsides, railroads.

Origin - Native to the southeastern U.S., West Indes and Central America.

Other info. - This species is sporadic and uncommon in Missouri, collected from just a handful of counties. The plant, although from a semi-tropical climate, is remarkably well adapted to colder and drier conditions.

The family Papaveraceae is famous for the secondary compounds contained in the plant tissues. Papaver somniferum is the infamous opium poppy, containing a witch's brew of over 40 physiologically active alkaloids. The dried sap of the plant is called opium, and this is the primary source of morphine, codeine, heroin, and other related compounds which are medicinally useful but also a huge scourge due to their addiction and abuse potential. Other plants in the family contain varying amounts of many of these alkaloids, and in fact consumption of poppy seed muffins or cake would lead to a positive opiate drug test if the detection threshold were not set (by law) at a level which avoids this. Argemone mexicana contains such alkaloids as sanguinarine, berberine, protopine, and others.

Photographs taken in Kissimmee, FL., 2-12-03, and in Winter Haven, FL., 12-23-03.


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