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claspingleaf St. Johnswort, small-flower St. John's wort

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

Leaves

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

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.

Inflorescences

laxly corymbiform to cylindric, (1–)5–65-flowered, branching mostly dichasial.

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.

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.

Capsules

narrowly conic-ellipsoid, 3–5 × 1.5–2 mm, usually broadest at or near middle.

Seeds

not carinate.

0.5–0.6 mm;

testa finely linear-scalariform.

2n

= 16.

Hypericum sect. Brathys

Hypericum gymnanthum

Phenology Flowering summer (Jun–Sep).
Habitat Bogs, ditches, open and cleared woods, damp habitats
Elevation 0–400 m [0–1300 ft]
Distribution
North America; Mexico; Central America; South America; West Indies; Africa; Asia; Pacific Islands (New Zealand); Australia
from FNA
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)]
[WildflowerSearch map]
[BONAP county map]
Discussion

Species 148 (16 in the flora).

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

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.)

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
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. harperi, H. hypericoides, H. kalmianum, H. lissophloeus, H. lloydii, H. lobocarpum, H. maculatum, H. majus, 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
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
Synonyms section Brathys, H. section Brathys, H. section Spachium, H. subsection Spachium, H. section Trigynobrathys, Sarothra section Trigynobrathys H. canadense var. cardiophyllum, H. mutilum var. gymnanthum, Sarothra gymnantha
Name authority unknown Engelmann & A. Gray: Boston J. Nat. Hist. 5: 212. (1845)
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