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greater Canada St. John's-wort, greater Canadian St. John's-wort, large Canadian St. John's-wort, large St. John's wort, millepertuis majeur

dwarf St. John's-wort, small Canadian St. John's-wort, small flower st john's wort

Habit Herbs perennial, erect, branching at base and in inflorescence, branches relatively few, 0.5–7 dm. 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.
Stems

internodes 4-angled.

internodes 4-angled.

Leaves

spreading, sessile or distal subamplexicaul;

blade lanceolate to narrowly oblong-elliptic or (proximal) oblanceolate, 10–45 × (2–)6–12 mm, papery to membranous, margins plane, apex acute to rounded, basal or near-basal veins (3–)5–7, midrib with to 4 pairs of branches.

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.

Inflorescences

corymbiform to cylindric, 3–30-flowered, usually compact, branching mostly dichasial.

cylindric, 5–60-flowered, branching mostly dichasial;

bracts linear-subulate.

Flowers

6–7 mm diam.;

sepals lanceolate to narrowly elliptic, equal, 3.5–6.5 × 0.8–1.5 mm, margins sometimes ciliate, not setulose-ciliate, apex acute;

petals golden yellow, sometimes red-veined, oblanceolate, 3.5–6 mm;

stamens 12–21, obscurely 5-fascicled;

styles 0.6–1 mm;

stigmas broadly capitate.

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.

Capsules

narrowly conic-ellipsoid, 4–8 × 2.5–3.5 mm, broadest proximal to middle.

narrowly ovoid to cylindric-ellipsoid, 2–5 × 1.6–2.4 mm, usually broadest at or near middle.

Seeds

0.5–0.7 mm;

testa finely linear-scalariform.

0.4–0.7 mm;

testa finely linear-scalariform.

2n

= 16.

Hypericum majus

Hypericum mutilum

Phenology Flowering summer (Jun–Sep).
Habitat Fens, marshes, ditches, lake and stream margins, other damp habitats
Elevation 0–1200 m (0–3900 ft)
Distribution
from FNA
CO; CT; IA; ID; IL; IN; KS; MA; ME; MI; MN; MO; MT; ND; NE; NH; NJ; NY; OH; OR; PA; RI; SD; VT; WA; WI; AB; BC; MB; NB; NS; ON; PE; QC; SK [Introduced in Europe (France, Germany), e Asia (Japan)]
[WildflowerSearch map]
[BONAP county map]
from FNA
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]
[WildflowerSearch map]
[BONAP county map]
Discussion

Hypericum majus was the western member of a vicariant species pair, differing from the originally eastern member (H. canadense) by the broader leaves, usually more-congested inflorescence, and larger flowers. These species became sympatric in glaciated northeastern North America and now hybridize freely, notably in Wisconsin (F. H. Utech and H. H. Iltis 1970). Hybrids are intermediate in form between the parents and have also been recorded from Connecticut, Massachusetts, and New Hampshire. Hypericum majus hybridizes also with H. mutilum, with subsp. mutilum in Maine, and with subsp. boreale in Michigan and Wisconsin.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Subspecies 2 (2 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Stems: apical internode shorter than adjacent one or almost absent; inflorescences: branching mostly dichasial from 2–10 nodes.
subsp. mutilum
1. Stems: apical internode usually longer than adjacent one; inflorescences: branching from 1–4(–6) nodes, branches diffuse and repeatedly monochasial distally.
subsp. latisepalum
Source FNA vol. 6, p. 91. FNA vol. 6, p. 93.
Parent taxa Hypericaceae > Hypericum > sect. Brathys Hypericaceae > Hypericum > sect. Brathys
Sibling taxa
H. adpressum, H. anagalloides, H. apocynifolium, H. ascyron, H. boreale, H. brachyphyllum, H. buckleyi, H. canadense, H. canariense, H. chapmanii, H. cistifolium, H. concinnum, H. crux-andreae, H. cumulicola, H. densiflorum, H. denticulatum, H. dolabriforme, H. drummondii, H. edisonianum, H. ellipticum, H. erythreae, H. fasciculatum, H. frondosum, H. galioides, H. gentianoides, H. graveolens, H. gymnanthum, H. harperi, H. hypericoides, H. kalmianum, H. lissophloeus, H. lloydii, H. lobocarpum, H. maculatum, H. microsepalum, H. mutilum, H. myrtifolium, H. nitidum, H. nudiflorum, H. paucifolium, H. perforatum, H. prolificum, H. pseudomaculatum, H. punctatum, H. radfordiorum, H. scouleri, H. setosum, H. sphaerocarpum, H. suffruticosum, H. tenuifolium, H. tetrapetalum, H. virgatum, H. ×mitchellianum
H. adpressum, H. anagalloides, H. apocynifolium, H. ascyron, H. boreale, H. brachyphyllum, H. buckleyi, H. canadense, H. canariense, H. chapmanii, H. cistifolium, H. concinnum, H. crux-andreae, H. cumulicola, H. densiflorum, H. denticulatum, H. dolabriforme, H. drummondii, H. edisonianum, H. ellipticum, H. erythreae, H. fasciculatum, H. frondosum, H. galioides, H. gentianoides, H. graveolens, H. gymnanthum, H. harperi, H. hypericoides, H. kalmianum, H. lissophloeus, H. lloydii, H. lobocarpum, H. maculatum, H. majus, H. microsepalum, H. myrtifolium, H. nitidum, H. nudiflorum, H. paucifolium, H. perforatum, H. prolificum, H. pseudomaculatum, H. punctatum, H. radfordiorum, H. scouleri, H. setosum, H. sphaerocarpum, H. suffruticosum, H. tenuifolium, H. tetrapetalum, H. virgatum, H. ×mitchellianum
Subordinate taxa
H. mutilum subsp. latisepalum, H. mutilum subsp. mutilum
Synonyms H. canadense var. majus, H. mutilum var. longifolium, Sarothra major Sarothra mutila
Name authority (A. Gray) Britton: Mem. Torrey Bot. Club 5: 225. (1894) Linnaeus: Sp. Pl. 2: 787. (1753)
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