This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Hypericum perforatum L. Sp. Pl. 785. 1753.
Perennial, herbaceous from a woody base, 1°-2° high, much branched. Stems erect, with numerous barren shoots at base; leaves sessile, oblong or linear, s"-10" long, 1"-4" wide, obtuse, more or less black-dotted; cymes terminal, several-many-flowered; flowers bright yellow, 8"-12" broad; sepals lanceolate, acute, shorter than the copiously black-dotted petals; stamens united at their bases into 3 sets; styles 3; capsule ovoid, 2"-3" long, 3-celled, glandular.
In fields and waste places, common throughout our area except the extreme north, and in the Southern States. Naturalized from Europe. Often a troublesome weed. Native also of northern Asia. June-Sept. English names, amber, penny-john, rosin-rose, herb-john. Johnswort. Cammock. Touch-and-heal. Crushed herbage odorous.
1803. H. subpetiolatum Bicknell; Small, Fl. SE. U.
S. 790. 1903.
Herbaceous, perennial from a woody base, erect, 1 1/2°-3° high. Leaves sessile, short-petioled, or partly clasping, oblong or ovate-lanceolate, obtuse, 1'-3' long, 4"-8" wide, copiously black-dotted; cymes terminal, many-flowered; pedicels about 1" long; flowers much crowded, 4"-7" broad; sepals ovate-oblong, acute, about half as long as the conspicuously black-dotted petals; stamens numerous, united in 3 or 5 sets; styles 3, variable in length; capsule ovoid, 2"-3" long, completely 3-celled.
In moist soil, Quebec and Ontario to Minnesota, Florida and Kansas. June-Sept.
Hypericum pseudomaculatum Bush; Britton, Man. 627. 1901.
Similar to the preceding species, but the leaves, at least the upper ones, acute, ovate to oblong-lanceolate; flowers larger; sepals lanceolate to ovate-lanceolate, acuminate; petals pale yellow, three to five times as long as the sepals, sometimes 10" long; capsule completely 3-celled, narrowly ovoid, 3"-4" long.
Hypericum graveolens Buckley, Am. Journ. Sci. 45: 174. 1843.
Herbaceous, perennial, similar to the preceding species. Stem erect, 1°-3° high, branched above; leaves oval, ovate or elliptic-oblong, sessile or clasping, obtuse, 1'-3' long, 1/2'-1' wide, sparingly black-dotted; cymes terminal, few-several-flowered; pedicels 1"-4" long; flowers usually crowded, 1' in breadth or more; sepals lanceolate, acute, much shorter than the sparingly dotted or dotless petals; stamens united in sets; styles 3; capsule ovoid, somewhat 3-lobed, 3-celled, 4"-6" long.
Mountains of southwestern Virginia, Tennessee and North Carolina. June-Sept.