Arctium minus Bernh.

Burdock

Arctium minus plant2

Family - Asteraceae

Habit - Large, coarse, biennial forb with stout taproot.

Stems - Ascending, to 1.8 m, usually branched, stout, longitudinally ridged, minutely hairy, at least toward the tip, often reddish- or purplish-tinged.

Arctium minus stemStem and node.

Leaves - Basal and alternate, long-petiolate. Petioles sparsely pubsescent, to 40 cm, with adaxial groove, typically hollow. Basal leaf blades to 60 cm long, ovate, cordate at the base, bluntly or sharply pointed at the tip, the margins irregularly wavy, crisped, or shallowly lobed and often also toothed, the upper surface glabrous or with scattered hairs along the main veins, the undersurface pale-colored, sparsely to moderately pubescent with minute, few-branched hairs, sometimes becoming nearly glabrous with age. Stem leaves progressively smaller toward the tip.

Arctium minus leaf1Basal leaf.

Arctium minus leaf2Leaf abaxial.

Arctium minus leafBasal leaf and size 10 hiking boot.

Inflorescence - Inflorescences axillary and terminal, the heads sessile or short-stalked, appearing clustered or more commonly in short, dense racemes. Peduncles tomentose.

Arctium minus inflorescenceInflorescence.

Heads - Discoid, the involucre broadly ovoid to nearly spherical, 1.2-2.5 cm in diameter, the florets all perfect. Receptacle flat, with numerous chaff bristles. Involucral bracts 4-13 mm long, the body narrowly lanceolate, appressed-ascending, glabrous or somewhat glandular, tapered to a long, stiff, ascending bristle, this hooked at the tip. Involucre becoming slightly enlarged and globose in fruit.

Arctium minus headHead, sectioned.

Ray florets - Absent.

Disc florets - Corollas 7-9 mm long, pink to purple, glabrous, often somewhat glandular, 5-lobed, the lobes acute, 1.3mm long. Stamens 5, adnate at apex of constricted portion of corolla tube. Filaments white, glabrous, 3.5 mm long. Anthers purple, connate around style, exserted, 3 mm long. Style bifurcate, white, pubescent at base of stigmas. Pappus of several unequal series of short, flattened, bristlelike awns, these 1-3 mm long, with short, ascending barbs, mostly shed individually by fruiting.

Fruits - July - September. Achenes to 6 mm long, oblong or slightly narrower at the symmetrical base, somewhat flattened, the surface finely wrinkled, grayish brown with darker mottling.

Flowering - July - October.

Habitat - Pastures, roadside ditches, low woods, streambanks.

Origin - Native to Europe.

Other info. - This coarse plant is found scattered sporadically throughout most of the state, and is found in nearly all of the continental U.S. except Texas and Florida. The combination of large basal leaves and the numerous flowering heads with hooked phyllaries make this plant easy to identify. It's wise to avoid contact with the plant late in the year, as the fruiting heads grab onto nearly everything. Absent humans, the burlike heads are dispersed mainly in animal fur.

Young stems of burdock are eaten fresh or (more commonly) baked or boiled, and young foliage is eaten by livestock. The thick roots can be cooked and eaten, and in the past they sometimes were dried and ground for use as a coffee extender similar to chicory. The roots also have been used medicinally as a laxative, diuretic, and to treat rheumatism, burns, and sores. Most plants have pink to light reddish purple disk corollas. The color variation has formed the basis of species subdivisions published by some authors.

Photographs taken at Geneva State Park, Geneva, Ohio, 8-4-00, and at Whirlpool State Park, Niagra Falls, NY., 8-6-00 (DETenaglia); also at Weldon Spring Conservation Area, St. Charles County, MO, 9-1-2007, and near Labadie, Franklin County, MO, 7-29-2014 (SRTurner).


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