Spiny Leaf Sow Thistle - Hare Lettuce
Sonchus asper - (Linnaeus) Hill
Asteraceae (Sunflower - Aster) Family

Plant is a winter or spring annual that may be 1-6' tall, branching very little except near where the flowerheads occur. Its central stem is hairless and dull green; sometimes tinted with reddish- purple.

The leaves are alternate on the stem and may be upwards to 10 inches long and 2.5 inches across, becoming smaller and more sparsely distributed as they ascend the central stem. Each leaf is odd pinnate (pinnatifid) with deep triangular lobes; margins are dentate with soft prickles. The upper leaves are entire or have shallow lobes. Like the central stem, each leaf has a dull green hairless upper surface and may be tinted reddish-purple toward the base. At the is usually a pair of pointed basal lobes that extend beyond the stem.

The flower heads are in clusters that are about 3/4 inch across when fully open. Flowers emerge during the morning hours and close by noon. Each flowerhead consists of numerous yellow ray florets and no disk florets. The floral bracts at the base are dull green, hairless, and overlap each other. The blooming period occurs from late spring to mid-summer and lasts about a month in a given locale; a few plants may bloom later in the year.

Fruit is achene with tufts of fluffy white hairs. The achene is somewhat flattened, ribbed, and oblong in outline with one end being broader than the other. Distribution of the achenes is by the wind.
Spiny Leaf Sow Thistle is an introduced herbaceous annual or short-lived perennial in the Sunflower family (Asteraceae). It is native to Europe, North Africa, and western Asia. In Alabama it can be found state wide. Spiny Leaf Sow Thistle grows on roadsides, in vacant lots, along railroad tracks, in fallow fields, and in other disturbed, sunny habitats. It is an annual or short-lived perennial with a tap root. The stem is 1-3 feet in height, hollow, glabrous, with prominent longitudinal ribs. The leaves are cauline and basal. The basal leaves form a rosette that may not be present at flowering. The leaves are alternate, glabrous, oblong to lanceolate in outline, with lobed and prickly toothed margins. The leaves have large rounded auriculate bases that clasp the stem and winged petioles. All parts of the plant exude a milky white latex sap when damaged. Flowers are produced in heads. The heads are on stipitate glandular peduncles. The head is composed of yellow ray flowers and no disc flowers. The fruit is an achene with a tuft of white pappus. -- Dr. Al Diamond

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