Verbascum thapsus is a biennial herb from a deep taproot, all parts densely wooly (the only plant in our area with this thick, wooly, flannel-like texture and very pale, gray-green color).
Leaves alternate, in a winter basal rosette first year, large to 60 cm diameter, blades pale grayish green with dense wooly felt-like hairs, larger leaves to 30 cm long, oblong, entire, thick; stem leaves of second year alternate, progressively reduced, sessile, base extending down stem as wings.
Flowers yellow, about 2 cm, radially symmetrical, 5 parted, inflorescence a dense spike, to 50 cm long, 3 cm wide, usually unbranched, flowering upward along stalk. Pollinated by bees, also self-fertile (autogamous) (Mulligan and Kevan 1973), June-Aug.
Fruit dry capsules splitting open to release numerous tiny, wind-dispersed seeds, seeds can be viable for 100 years; seeds germinate in early spring, flowers second year, winter plants tall, with seed capsules densely crowded along stout spike (Levine 1995), seeds need bare ground to germinate and grow, shade intolerant. (Gross and Werner 1978).
Wetland status: UPL.
Frequency in NYC: Frequent.
Habitat: Open, disturbed areas, roadsides, sandy fill, prefers pH 6.5-7.8 (Hoshovsky, 1995a).
Notes: Host to the powdery mildew, Erysiphe cichoracearum, a pest of several agricultural crops. Host to the European curculionid weevil, Gymnaetron tetrum that is specific to common mullein and destroys up to 50% of seeds in each capsule and may induce branching of the flowering stalk (Naber and Aarssen 1998). Host to the fungi Cercospora verbasciola, Phymotrichium omnivorum, Phoma thapsi and Phyllosticta verbasciola, among others. Mullein has been used as a medicinal herb for millennia, thought to be the “phlemos” of Hippocrates. Introduced in 1700s as medicinal and fish poison (Gross and Werner 1978).