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.