Hypericum gymnanthum |
Hypericum perforatum |
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claspingleaf St. Johnswort, small-flower St. John's wort |
Chase-devil, common St. John's-wort, Klamath weed, millepertuis commun, Tipton's weed |
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Habit | Herbs annual, usually erect, sometimes shortly decumbent and rooting, basal branches none, rarely with 1–3(–6) pairs of narrowly ascending branches distally, 0.6–7 dm. | |
Stems | internodes 4-angled. |
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Leaves | spreading, sessile or amplexicaul; blade usually ovate-triangular to broadly ovate, rarely oblong (mid and distal blades lanceolate-deltate), 5–25 × 3–12 mm, papery to membranous, margins plane, apex usually subacute, basal veins (3–)5, midrib usually with 1–2 pairs of branches. |
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Inflorescences | laxly corymbiform to cylindric, (1–)5–65-flowered, branching mostly dichasial. |
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Flowers | 4.5–7 mm diam.; sepals lanceolate to narrowly ovate, equal, 3–5 × 0.8–1.2 mm, margins sometimes ciliate, not setulose-ciliate, apex acute to acuminate; petals bright yellow, oblanceolate, 2–4 mm; stamens 10–14, scarcely grouped; styles 0.5–0.7 mm; stigmas broadly capitate. |
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Capsules | narrowly conic-ellipsoid, 3–5 × 1.5–2 mm, usually broadest at or near middle. |
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Seeds | 0.5–0.6 mm; testa finely linear-scalariform. |
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2n | = 16. |
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Hypericum gymnanthum |
Hypericum perforatum |
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Phenology | Flowering summer (Jun–Sep). | |
Habitat | Bogs, ditches, open and cleared woods, damp habitats | |
Elevation | 0–400 m (0–1300 ft) | |
Distribution |
AL; AR; DE; FL; GA; IL; IN; LA; MD; MO; MS; NC; NJ; OH; PA; SC; TN; TX; VA; Central America (Guatemala) [Introduced Atlantic Islands (Azores)]
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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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Discussion | Hypericum gymnanthum was introduced into Poland; it is now extinct there. It is closely related to H. mutilum; it differs from that species in the broader, usually deltate leaves; fewer, stricter branches; no condensed apical stem internode; and larger flowers with lanceolate to ovate sepals. Hybrids of Hypericum gymnanthum with H. mutilum have been reported from Maryland, Mississippi, North Carolina, Tennessee, and West Virginia, and, perhaps erroneously, with H. canadense from Virginia. Hypericum gymnanthum has clearly been introduced (recently?) into the Azores, not necessarily by man. Seeds may well have been carried there by birds. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 6, p. 93. | FNA vol. 6, p. 99. |
Parent taxa | Hypericaceae > Hypericum > sect. Brathys | Hypericaceae > Hypericum > sect. Hypericum |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | H. canadense var. cardiophyllum, H. mutilum var. gymnanthum, Sarothra gymnantha | |
Name authority | Engelmann & A. Gray: Boston J. Nat. Hist. 5: 212. (1845) | Linnaeus: Sp. Pl. 2: 785. (1753) |
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