Spiny Sowthistle, Sonchus asper
Family: Asteraceae; Sunflower Family
Vegetative Characteristics:
Seedling: cotyledons roundish, grayish green; first true leaves from a rosette, blades oblong to ovate, delicate prickles around margins, pale green on underside
Stems: erect, 0.1-0.5 m tall, coarse, hollow, milky sap, upper half of main stem often branched
Leaves: alternate, 6.0-30.0 cm long, 2.0-10.0 cm wide, lanceolate to oblanceolate, lower leaves deeply lobed, gradually reduced apically with irregularly toothed margins and sharp-pointed prickles, rounded earlike projections clasping set at leaf base
Reproductive Characteristics:
Inflorescences: numerous small heads, 9.0-13.0 mm tall, 1.2-2.5 cm wide; bracts numerous, 9.0-13.0 mm long; ray florets bright yellow
Fruits: achene, 2.5-3.0 mm long; reddish brown, flat 3-5 ribbed on each side; pappus crowned with tufts of long white trichomes
Special Identifying Characteristics:
⇒ erect annual; stems hollow with milky sap; leaves alternate, deeply lobed with prickly spines along margins; flowers bright yellow, borne in small heads
