Hypericum densiflorum


Fl. Amer. Sept. 2: 376. 1813.

Common names: Bushy St. John’s wort
Synonyms: Hypericum glomeratum Small H. interior Small H. nothum Rehder H. prolificum var. densiflorum (Pursh) A. Gray
Treatment appears in FNA Volume 6. Treatment on page 78. Mentioned on page 75, 76.

Shrubs, erect, forming slender bush, 6–30 dm. Stems: internodes 4-lined at first, soon 2-lined to terete. Leaf blades narrowly elliptic-oblong or oblanceolate to linear, 20–45 × 2–7 mm, base articulated, narrowly cuneate to attenuate, margins recurved to revolute, apex apiculate-rounded to subacute, midrib with 14–17 pairs of branches. Inflorescences broadly pyramidal to broadly cylindric, 5–25-flowered from apical node, with (2–)5–15-flowered dichasia from 1–2 proximal nodes. Flowers 10–17(–20) mm diam.; sepals deciduous, not enclosing capsule, 5, narrowly oblong to oblanceolate-spatulate, unequal or subequal, 4–6 × 1–1.5 mm, basal veins 1–3; petals 5, deep golden yellow, obovate-oblanceolate, 6–9 mm; stamens deciduous, 100–150; ovary 3–4(–5)-merous. Capsules narrowly ovoid conic to cylindric-ovoid, 5–6(–7) × 2–3 mm, not or scarcely lobed. Seeds not carinate, 0.8–1.3 mm; testa linear-reticulate. 2n = 18.

Phenology: Flowering summer (Jun–Aug).
Habitat: Wet or moist habitats (meadows, lake margins, pinelands, etc.), road embankments, rocky hillsides
Elevation: 0–1000 m


V6 120-distribution-map.jpg

Ala., Del., Ga., Ky., Md., N.J., N.C., Pa., S.C., Tenn., Va., W.Va.


Hybrid intermediates between Hypericum densiflorum and H. lobocarpum occur in northwestern Alabama, and a narrow-leaved, small-flowered form in Tennessee and northern Georgia (H. interior) verges toward H. galioides. Hypericum densiflorum is always distinct from H. prolificum in the wild; these species hybridize in gardens. Hypericum ×arnoldianum Rehder, known in cultivation only, was thought by Rehder to have the parentage H. galioides × lobocarpum; on both morphological and cytological grounds, the conclusion of W. P. Adams (1972) that it was H. densiflorum × lobocarpum seems much more likely.

Selected References


Lower Taxa

... more about "Hypericum densiflorum"
Norman K. B. Robson +
Undefined sect. Myriandra +
Bushy St. John’s wort +
Ala. +, Del. +, Ga. +, Ky. +, Md. +, N.J. +, N.C. +, Pa. +, S.C. +, Tenn. +, Va. +  and W.Va. +
0–1000 m +
Wet or moist habitats (meadows, lake margins, pinelands, etc.), road embankments, rocky hillsides +
Flowering summer (Jun–Aug). +
Fl. Amer. Sept. +
Hypericum glomeratum +, H. interior +, H. nothum +  and H. prolificum var. densiflorum +
Hypericum densiflorum +
Hypericum sect. Myriandra +
species +