§ 2. Stamens very numerous, obscurely if at all clustered; styles 3 (n. 2 excepted), more or less united into one, the stigmas not capitate except in n. 10; sepals mostly foliaceous.
[*] Bushy shrubs, 1–6° high, leafy to the top.
[+] Styles 5; pod completely 5-celled.
2. H. Kalmiànum, L. (Kalm's St. John's-wort.) Branches 4-angled; branchlets 2-edged; leaves crowded, glaucous, linear to oblanceolate (1–2´ long); flowers few in a cluster (1´ wide); pods ovate.—Wet rocks, Niagara Falls and northern lakes. Aug.
[+][+] Styles 3; pod completely 3-celled.
3. H. prolíficum, L. (Shrubby St. John's-wort.) Branchlets 2-edged; leaves narrowly oblong (1–2´ long), mostly obtuse, narrowed at the base; flowers numerous, in single or compound clusters; pods lanceolate to ovate, 4–6´´ long.—N. J. to Mich., Minn., and southward. July–Sept.—Varies greatly in size, etc.
4. H. densiflòrum, Pursh. Exceedingly branched above, 1–6° high, the branches slender and crowded with smaller leaves; flowers smaller (½–{2/3}´ in diameter) and more numerous, in crowded compound cymes; pod 2–3´´ long. (H. prolificum, var. densiflorum, Gray.)—Pine barrens of N. J. to glades of Ky., Ark., and southward.
[*][*] Perennial herbs or a little woody at the base.
[+] Pod incompletely 3–4-celled.
5. H. galioìdes, Lam. Slender, branching, woody below; leaves linear-oblanceolate, narrowed downward, ½–3´ long, mostly acute; flowers small in terminal and axillary cymes; sepals very narrow, 1½–3´´ long; pod as long, ovate.—Del. to Ga. and E. Tenn.