Sonchus asper , or Prickly Sowthistle, is a spring or summer annual herbaceous wildflower, with spiney leaves and yellow flowers and is often considered a weed because of its aggressive spread. Prickly Sowthistle typically grows in full sun, moist to slightly dry conditions, and different kinds of soil, including loam, clay-loam, and shallow gravelly soil. It is often found in lawns, waste places, and roadsides.The size of this plant varies depending on the moisture and fertility of the soil. It can bolt upward and form flowerheads very quickly during the summer. In a garden setting, be careful not to let this plant go to seed. The seeds spread by wind and water and the plant can tend to take over a site. The plant is not frost tender and flowers from June to August. The seeds ripen from July to September.
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
Full sun (6 or more hours of direct sunlight a day)
Soil texture
Clay; Loam (Silt); Shallow Rocky
Soil drainage
Moist | Occasionally Dry
Growth rate
Rapid
Maintenance
Low
Canopy layer
4 - Herbaceous
Form & Appearance
Habit / form
Erect
Texture
Coarse
Leaf color
Green
Leaf type
Simple
Leaf arrangement
Alternate
Leaf shape
Lanceolate; Oblanceolate; Pinnatifid
Leaf margin
Entire
Leaf feel
Glossy
Leaf size
> 6 inches long, 3-6 inches wide
Hairs present
No
Leaf detail
Large basal leaves and smaller, curved upper leaves have soft, very spiny teeth. Margins are spiny and wavy, white mid-vein, large round basal lobes clasping - curled downward, often dark green and glossy. Leaves are up to 10 inches long and 3½ inches across, but more commonly they are about half this size or less. On shorter plants, they are rather crowded together on the stems, even where the composite flowers occur. Depending on the local form of the plant, these leaves may be pinnatifid, or they may lack significant lobes along the margins, in which case they are broadly lanceolate or oblanceolate.
Flower color
Gold/Yellow
Flower size
< 1 inch
Flower detail
The upper stems terminate in clusters of 1 to 5 composite flowers on rather short stalks. Each flower is about 2/3 inch across when fully open, consisting of numerous yellow ray florets. The base of each flower is covered with dull green bracts and is it rather short. The blooming period can occur from late spring to early fall, and usually lasts about a month for a colony of plants.
Bloom time
Spring; Summer
Fruit color
Black
Fruit type
Achene
Fruit detail
Each floret is replaced by an achene with a tuft of silky white hairs. The achenes are flat, spindle-shaped, hairless, and have several longitudinal ribs. They are distributed by the wind. This plant spreads by reseeding itself.
Stem color
Green
Stem detail
Upright, smooth, stems branched sparsely above. The stems have rather conspicuous longitudinal veins and are usually hairless, although occasionally the upper stems and flowering stalks have a few hairs.