Hypericum perforatum |
Hypericum densiflorum |
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Chase-devil, common St. John's-wort, Klamath weed, millepertuis commun, Tipton's weed |
bushy St. John's-wort, dense St. Johnswort |
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Habit | Shrubs, erect, forming slender bush, 6–30 dm. | |
Stems | internodes 4-lined at first, soon 2-lined to terete. |
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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. |
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Inflorescences | broadly pyramidal to broadly cylindric, 5–25-flowered from apical node, with (2–)5–15-flowered dichasia from 1–2 proximal nodes. |
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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. |
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Capsules | narrowly ovoid conic to cylindric-ovoid, 5–6(–7) × 2–3 mm, not or scarcely lobed. |
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Seeds | not carinate, 0.8–1.3 mm; testa linear-reticulate. |
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2n | = 18. |
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Hypericum perforatum |
Hypericum densiflorum |
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Phenology | Flowering summer (Jun–Aug). | |
Habitat | Wet or moist habitats (meadows, lake margins, pinelands, etc.), road embankments, rocky hillsides | |
Elevation | 0–1000 m [0–3300 ft] | |
Distribution |
AR; CA; CO; CT; DC; DE; IA; ID; IL; IN; KS; KY; MA; MD; ME; MI; MN; MO; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; VA; VT; WA; WI; WV; WY; BC; MB; NB; NF; NS; ON; PE; QC; Europe; Asia (sw Arabia, China, India, Mongolia, Siberia); n Africa [Also introduced widely elsewhere]
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AL; DE; GA; KY; MD; NC; NJ; PA; SC; TN; VA; WV
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Discussion | Subspecies 4 (1 in the flora). Hypericum perforatum has been introduced into various parts of the world, including North America, where only subsp. perforatum is represented. The range of variation in the flora area is less than occurs in Europe, and signs of hybridization that are common there are absent in North America. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 6, p. 99. | FNA vol. 6, p. 78. |
Parent taxa | ||
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | H. glomeratum, H. interior, H. nothum, H. prolificum var. densiflorum | |
Name authority | Linnaeus: Sp. Pl. 2: 785. (1753) | Pursh: Fl. Amer. Sept. 2: 376. (1813) |
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