Prickly cow thistle, sow thistle
All states (non native)
Roadsides, fields, disturbed ground
Lancelolate, bluish-green, hairless, up to 12 inches long, with lobed edges; tip of each lobe forms a soft spine
February to August
Like many thistle species, sonchus asper is not native to the US, originating from Europe, but it has become established in every state. The yellow, dandelion-like flowers form a cluster at the top of the thick, hollow, ridged stems (filled with milky sap); they are composed of up to 150 thin ray florets and dozens of short stamens, branched at the tip, and they have a diameter of one inch when fully open. The largest leaves grow around the base; those higher up the stem are smaller, clasping via basal lobes, and they have an alternate arrangement. The seeds also resemble those of a dandelion, forming a feathery white ball.