1. Woody shrub (mostly dying back nearly to the ground in Michigan); corolla 4-lobed; stamens 4; flowers purple.

Buddleja

1. Herbs; corolla 5-lobed; stamens 5 (4 plus a staminodium (sterile filament) lying under the upper corolla lobe in Scrophularia, with brown to greenish flowers); flowers white, yellow, greenish, or brownish, rarely pink.

2. Cauline leaves all or mostly opposite on fertile stems; corolla brownish, clearly bilaterally symmetrical and ± 2-lipped.

Scrophularia

2. Cauline leaves all or mostly alternate on fertile stems (lowermost leaves sometimes opposite and rosette of larger basal leaves sometimes present); corolla yellow, white, or pinkish, nearly regular.

Verbascum