Parts of all states; most common towards the west (non-native)
Disturbed areas, roadsides, fields, up to 4,500 feet
Basal leaves are divided into wavy-edged lobes; stem leaves are narrow and lanceolate
January to August
Brassica rapa originates in Europe but is cultivated all across the world, and naturalized in some parts of all the US states; in the west it is most common in California and Oregon. Basal leaves are divided into several pairs of irregularly-shaped lobes, and a large, obovate, terminal lobe; all lobes have wavy edges. Stem leaves are smaller, narrower, generally unlobed, and clasping at the base. Stems are freely branching, topped by clusters of small flowers.
Buds are green, opening to four greenish-yellow sepals and four yellow petals half an inch in length. The fruit is a narrow green pod, widest towards the base, 4 inches long and less than a quarter of an inch across. Fruits point upwards.