This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Introduced. Biennial. Propagates by seeds.
Time of bloom: June to October.
Seed-time: July to November.
Range: Quebec to Minnesota, southward to Florida and Kansas. Habitat: Clover fields, meadows, pastures, and waste places.
A more pernicious weed than the preceding species, its invasion of grasslands causing the seeds to become mixed with those of timothy and other grasses, from which they are difficult to remove. The leaves are said to repel the cockroach (Blatta), whence the specific name; but the writer has not found the reputation merited.
Stem two to five feet high, round, slender, simple or occasionally branched, smooth or sparsely set with glandular hairs near the top. Lower leaves oblong, sometimes pinnatifid, smooth, dark green, veiny, double-toothed, three inches to nearly a foot in length, tapering to petioles; seldom present at flowering time; upper leaves alternate, pointed and partly clasping. Flowers in long, open racemes, on spreading pedicels nearly an inch long, with small, pointed bracts at the base; corolla about an inch broad, the five lobes unsymmetrical, creamy-white or pale yellow, the upper one brownish on the back; stamens of unequal lengths, the filaments bearded with purple hairs. Capsules globose, longer than the calyx, many-seeded. (Fig. 263.) Means of control the same as for Common Mullein.
Fig. 263. - Moth Mullein (Verbascum Blattaria). X 1/4.