Hypericum mutilum |
Hypericum boreale |
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dwarf St. John's-wort, small Canadian St. John's-wort, small flower st john's wort |
millepertuis bor é al, northern bog St. John's-wort, northern St. John's-wort |
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Habit | Herbs annual or perennial, usually erect, sometimes decumbent and rooting, basal branches sometimes present, usually with to 10 pairs of spreading branches distal to middle, 0.5–8 dm. | Herbs annual or perennial, erect, with decumbent to prostrate, rooting base, usually 2–6-branched, branches spreading or ascending distal to middle, 0.9–3.3 dm. | ||||
Stems | internodes 4-angled. |
internodes 4-angled, apical internode shorter than adjacent one or almost absent. |
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Leaves | spreading, sessile or amplexicaul; blade paler abaxially, ovate, elliptic, or elliptic-oblong (proximal), ovate or suborbiculate to elliptic or lanceolate (mid and distal), 3–27(–40) × 1–15 mm, papery to membranous, margins plane, apex obtuse to rounded, basal veins 3–5, midrib with to 3 pairs of branches. |
spreading, sessile; blade (concolor), broadly to narrowly oblong or elliptic to oblanceolate or round, 5–15 × 2–5 mm, papery to membranous, margins plane, apex rounded, basal veins 3–5, midrib branched or not. |
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Inflorescences | cylindric, 5–60-flowered, branching mostly dichasial; bracts linear-subulate. |
cylindric to rounded-pyramidal, 1–13-flowered, branching mostly dichasial; bracts not linear-subulate. |
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Flowers | 3–5 mm diam.; sepals lanceolate to linear-lanceolate or elliptic-oblong to oblanceolate, equal or unequal, 2–4.5 × 0.6–1.5 mm, margins sometimes ciliate, not setulose-ciliate, apex usually acute to apiculate, sometimes obtuse to rounded; petals pale yellow, oblong, 1.7–3.5 mm; stamens 5–16, scarcely grouped; styles 0.5 mm; stigmas broadly capitate. |
3–5 mm diam.; sepals usually lanceolate to narrowly oblong, rarely oblanceolate, equal, 2.5 × 0.8–1 mm, margins sometimes ciliate, not setulose-ciliate, apex rounded; petals pale yellow, oblong, 1.7–3.5 mm; stamens 5–16, scarcely grouped; styles 0.5 mm; stigmas broadly capitate. |
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Capsules | narrowly ovoid to cylindric-ellipsoid, 2–5 × 1.6–2.4 mm, usually broadest at or near middle. |
narrowly ovoid to cylindric-ellipsoid, 4–5 × 2–2.5 mm, usually broadest at or near middle. |
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Seeds | 0.4–0.7 mm; testa finely linear-scalariform. |
0.4–0.7 mm; testa finely linear-scalariform. |
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2n | = 16 [“18”]. |
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Hypericum mutilum |
Hypericum boreale |
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Phenology | Flowering summer–early fall (Jul–Sep). | |||||
Habitat | Bogs, poor fens, lake margins, marshes | |||||
Elevation | 0–500 m (0–1600 ft) | |||||
Distribution |
AL; AR; CA; CO; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MO; MS; NC; NE; NH; NJ; NY; OH; OK; OR; PA; RI; SC; TN; TX; UT; VA; VT; WA; WI; WV; BC; NB; NS; ON; QC; SK [Introduced in w North America]
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CT; DE; IA; IN; MA; MD; ME; MI; MN; NH; NJ; NY; OR; PA; RI; VA; VT; WA; WI; BC; MB; NB; NF; NS; ON; PE; QC; SPM |
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Discussion | Subspecies 2 (2 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Where Hypericum boreale grows submerged, the plants are almost always sterile with elongated stems and suborbiculate leaves (H. boreale forma callitrichoides Fassett). Such plants intergrade shorewards with typical H. boreale (F. H. Utech and H. H. Iltis 1970). All other chromosome counts for H. mutilum and its near relatives have given n = 8; B. M. Kapoor’s (1972) count of 2n = 18 must be treated with reserve. Hypericum mutile var. boreale (Britton) E. P. Bicknell is not a validly published name. The discovery of Hypericum boreale near the mouth of Fraser River at Vancouver in 1989 extends the distribution of this species across Canada almost to the Pacific coast; this occurrence is almost certainly the result of recent introduction. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 6, p. 93. | FNA vol. 6, p. 94. | ||||
Parent taxa | Hypericaceae > Hypericum > sect. Brathys | Hypericaceae > Hypericum > sect. Brathys | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Sarothra mutila | H. canadense var. boreale, H. mutilum subsp. boreale, Sarothra borealis | ||||
Name authority | Linnaeus: Sp. Pl. 2: 787. (1753) | (Britton) E. P. Bicknell: Bull. Torrey Bot. Club 22: 213. (1895) | ||||
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