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Hypericum - St. John's-wort
by Kerry Barringer
Not peer reviewed
Last modified: 03/03/2006
Nomenclature
Hypericum L., Sp. Pl. 783. 1753. Gen. Pl. 341. 1754. LECTOTYPE: Hypericum perforatum L., designated by Britton & Brown (1913).
Ascyrum L., Sp. Pl. 787. 1753. Gen. pl., ed. 5, 342. 1754. Hypericoides Adans., Fam. Pl. (Adanson) 2: 443. 1763. Myriandra Spach, Ann. Sci. Nat. Bot. ser. 2, 5: 364. 1836. LECTOTYPE: Hypericum hypericoides (L.) Crantz (Ascyrum hypericoides L.), designated by Britton & Brown (1913).
Brathys L. f., Suppl. Pl. 43, 268. 1782. TYPE: Brathys juniperina L.f.
Crookea Small, Fl. S.E. U.S. 786, 1335. 1903. TYPE: Crookea microsepalum (Torr. et A. Gray) Small.
Key to the species of Hypericum
1. Petals 4; sepals 4, very unequal, the outermost much larger that the 2
innermost...2
1. Petals 5 or rarely 4; sepals 5, equal to
subequal, sometimes with 1 sepal conspicuously larger than the rest...3
2. Decumbent; styles 2; stamens fewer than 50; leaves less than
7 mm wide...Hypericum hypericoides
2. Erect;
styles 3 or 4; stamens 50-100; leaves more than 7 mm...Hypericum crux-andreae
3. Sepals narrowly oblong, 4-6 mm long, 1-1.5 mm wide, acute;
leaves oblanceolate to elliptic 2-4 cm long, 2-6 mm wide; capsules ovoid, acute,
3 mm wide...Hypericum
densiflorum
3. Sepals ovate, elliptic, or foliaceous, more than 2 mm
long; leaves usually more than 1 cm wide...Hypericum prolificum