This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Speckled John. Introduced. Perennial. Propagates by seeds and by runners from the base of the stem. Time of bloom: June to September. Seed-time: July to October. Range: Throughout British America except in the far North, and in all the states except the most southern. Habitat: Fields, pastures, and waste places.
A most pernicious weed, difficult of suppression. When young its juices are so acrid and blistering that no grazing animal will eat the plant; and when mature or dried in hay, stock reject it because of its woody toughness. (Fig. 199.)
Stem ten to thirty inches tall, erect, slender, much branched, rather stiff, bearing along the sides two opposing ridges which make it two-edged. Leaves opposite, oblong to elliptic, one-half inch to
Fig. 199. - Common St. John's-wort (Hypericum perforatum). X 1/4 an inch long, light green, sessile, more or less black-dotted and specked all over with pellucid dots. Flowers in terminal cymose clusters, very showy; petals five, golden yellow, nearly a half-inch long, with black-dotted margins; stamens many, separated into three groups, their anthers black-dotted; styles three, divergent; calyx of five lance-shaped, acute sepals, specked with pellucid dots. Capsule ovoid, three-celled, filled with small, rounded, oblong seeds, their surface delicately pitted in rows. Too often an impurity among grass seeds.
The plant is best destroyed by hand-pulling when the soil is sufficiently soft to slacken its hold on the long, woody roots. Or it may be grubbed out, care being taken to leave no stray runners. A meadow or a pasture too rankly infested to be so cleansed should be turned under and put to a well-tilled hoed crop.