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

Habit Herbs, annual or perennial (stems and leaves glabrous except 43. H. setosum); black glands absent. 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.

Leaves

deciduous (base articulated) or persistent (base not articulated).

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

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

bracts linear-subulate.

Flowers

3–15 mm diam.;

sepals persistent, (4–)5;

petals persistent, (4–)5;

stamens persistent, (5–)10–80, usually in continuous or interrupted ring, sometimes in 5 barely discernable fascicles, each of 1–2 stamens;

ovary (2–)3(–4)-merous;

placentation parietal;

styles ± spreading, bases distinct;

stigmas capitate or clavate.

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

Seeds

not carinate.

0.4–0.7 mm;

testa finely linear-scalariform.

Hypericum sect. Brathys

Hypericum mutilum

Distribution
North America; Mexico; Central America; South America; West Indies; Africa; Asia; Pacific Islands (New Zealand); Australia
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]
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Discussion

Species 148 (16 in the flora).

(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. Herbs annual, wiry; inflorescences: branching mostly monochasial
→ 2
1. Herbs annual or perennial, not wiry; inflorescences: branching mostly dichasial
→ 3
2. Leaf blades linear or linear-subulate to linear-lanceolate, 5–22 mm, margins recurved to revolute; sepals 3–7 mm; capsule lengths 1–1.2 times sepals.
H. drummondii
2. Leaf blades narrowly triangular-subulate to linear-subulate, scalelike, 1–4 mm, margins incurved; sepals 1.5–2.5 mm; capsule lengths 2–2.7 times sepals.
H. gentianoides
3. Stems and leaves scabrous-tomentose to pilose; sepal margins setulose-ciliate.
H. setosum
3. Stems and leaves glabrous; sepal margins sometimes ciliate, not setulose-ciliate
→ 4
4. Leaf blades linear-subulate, 0.2–0.3 mm wide, basal veins 1, midrib unbranched.
H. cumulicola
4. Leaf blades not linear-subulate, (0.5–)2–18 mm wide, basal veins 1–7, midrib with 0–4 pairs of branches
→ 5
5. Leaf blades leathery; petals golden yellow or orange-yellow; stamens (35–) 50–80
→ 6
5. Leaf blades papery to membranous; petals usually bright, golden, or pale yellow, rarely salmon-orange; stamens 5–25
→ 11
6. Leaf blades linear-oblong or linear-lanceolate to linear, 0.5–2 mm wide; petals red tinged; stamens 35–50; styles 2.5–5 mm
H. paucifolium
6. Leaf blades elliptic, lanceolate, linear-lanceolate, oblong-elliptic, obovate, or ovate, 3–18 mm wide; petals not red tinged; stamens 50–80; styles 2–4 mm
→ 7
7. Herbs erect or ± spreading, non-aerenchymatous at base; leaves (main stems) longer than internodes
→ 8
7. Herbs erect to ascending, usually ± aerenchymatous (spongiform-thickened) at base; leaves (main stems) mostly shorter than internodes (usually longer in. 31 H. harperi).
→ 9
8. Leaf blades (main stem) lanceolate to oblong-elliptic or obovate, 10–30(–50) mm, apex usually acute to acuminate, rarely obtuse; subsidiary inflorescence branches with or without relatively smaller leaves.
H. virgatum
8. Leaf blades (main stem) narrowly lanceolate, 10–40(–55) mm, apex acute to acuminate; subsidiary inflorescence branches with relatively smaller leaves.
H. radfordiorum
9. Herbs 2–7 dm; leaf blades (main stem) usually broadly to narrowly ovate, rarely elliptic or lanceolate.
H. denticulatum
9. Herbs 3–12 dm; leaf blades (main stem) usually lanceolate, sometimes linear-lanceolate or oblong-elliptic, rarely elliptic or ovate
→ 10
10. Herbs erect to ascending, branching at base and in inflorescence; leaves strongly ascending to appressed, shorter than internodes, smaller distally.
H. erythreae
10. Herbs erect, branching (from long-creeping rhizomes) at base and from mid and distal nodes; leaves ascending to deflexed, mostly longer than internodes, not or scarcely smaller distally.
H. harperi
11. Herbs decumbent to ascending, forming loose mats; stigmas scarcely capitate.
H. anagalloides
11. Herbs usually erect, not forming loose mats; stigmas broadly capitate
→ 12
12. Leaf blades lanceolate, linear, narrowly elliptic, narrowly oblong-elliptic, oblanceolate, oblanceolate-linear, or obovate; capsules broadest proximal to middle
→ 13
12. Leaf blades usually elliptic, oblong, broadly oblong-elliptic, ovate, ovate-triangular, round, or suborbiculate, rarely lanceolate; capsules usually broadest at or near middle
→ 14
13. Leaf blades lanceolate, narrowly oblong-elliptic, or oblanceolate, (2–)6–12 mm wide, basal veins (3–)5–7; inflorescences usually compact.
H. majus
13. Leaf blades linear to oblanceolate-linear or (proximal) oblanceolate to obovate, 0.5–5.5 mm wide, basal veins 1–3(–5); inflorescences usually diffuse.
H. canadense
14. Leaf blades (mid and distal) lanceolate-deltate, apex usually subacute; capsules narrowly conic-ellipsoid.
H. gymnanthum
14. Leaf blades (mid and distal) elliptic, lanceolate, oblanceolate, oblong, round, suborbiculate, or ovate, apex obtuse to rounded; capsules narrowly ovoid to cylindric-ellipsoid
→ 15
15. Leaf blades bicolor, paler abaxially; inflorescences: bracts linear-subulate.
H. mutilum
15. Leaf blades concolor; inflorescences: bracts not linear-subulate.
H. boreale
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. 88. FNA vol. 6, p. 93. Treatment author: Norman K. B. Robson.
Parent taxa Hypericaceae > Hypericum 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. 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. anagalloides, H. boreale, H. canadense, H. cumulicola, H. denticulatum, H. drummondii, H. erythreae, H. gentianoides, H. gymnanthum, H. harperi, H. majus, H. mutilum, H. paucifolium, H. radfordiorum, H. setosum, H. virgatum
H. mutilum subsp. latisepalum, H. mutilum subsp. mutilum
Synonyms section Brathys, H. section Brathys, H. section Spachium, H. subsection Spachium, H. section Trigynobrathys, Sarothra section Trigynobrathys Sarothra mutila
Name authority unknown Linnaeus: Sp. Pl. 2: 787. (1753)
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