This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Pentstemon Iaevigatus, Ait. Var. Digitalis, Gray Native. Perennial. Propagates by seeds. Time of bloom: May to July. Seed-time: June to August. Range: New York to Illinois, southward to Virginia and Arkansas. Locally in the Northeastern States. Habitat: Meadows, pastures, and waste places.
An unwholesome and bitter weed which has been introduced in many new localities by means of baled hay and as an impurity of grain and grass seed. Cattle reject it when green, but will eat it as hay, when it is injurious to the flavor of dairy products.
Fig. 266. -Foxglove Beard-tongue (Pentstemon Ioevigatus var. Digitalis).
Stem rather stout, two to four feet tall, simple or branched from the base, often ruddy-colored, smooth except for the flower-stalks which are set with glandular hairs. Leaves opposite, light green, firm and glossy, long ovate to lance-shape, the upper ones sessile with clasping bases and the lower ones tapering to margined petioles. Panicle slender, many-flowered, terminal, the corolla about an inch long, whitish, tinged with reddish purple, the tube much dilated just behind the throat, which is open and not hairy; the five lobes are spreading and pointed, two on the upper lip, three on the lower; four stamens are fertile with purple anthers, and the sterile filament, or "tongue," is bearded only on its upper side; calyx-segments lance-shaped, acute. Capsule ovoid, two-celled, containing many irregular, angled seeds. (Fig. 266.)
Small areas may be destroyed by digging or pulling when the soil is soft, but meadows badly infested with Beard-tongue require to be put under cultivation for a season.