The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

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

Atlantic St. John's-wort

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. Shrubs, usually decumbent, not rooting, forming mats, 1–5 dm.
Stems

internodes 4-angled.

internodes 6-lined at first, becoming 4-lined, then terete.

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.

blades linear-subulate, 4–11 × 0.4–0.8 mm, base articulated, persistent, parallel or slightly expanded, margins revolute, apex rounded with ± prominent hydathode to long-acuminate, midrib unbranched.

Inflorescences

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

bracts linear-subulate.

± narrowly cylindric, 1–7-flowered, with 1(–3)-flowered dichasia from to 4 proximal nodes, rarely with 1 pair of flowering branches;

flowers sessile or nearly so.

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.

10–14 mm diam.;

sepals deciduous, not enclosing capsule, 5, linear-subulate, unequal, 2–4 × 0.4–0.5 mm;

petals 5, bright yellow, oblanceolate-oblong to obovate, 5–10 mm;

stamens deciduous, 50–90;

ovary 3-merous.

Capsules

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

narrowly (sub-)cylindric, (4–)5.7–9.5 × 1.5–2 mm.

Seeds

0.4–0.7 mm;

testa finely linear-scalariform.

scarcely carinate, 0.5 mm;

testa coarsely reticulate.

2n

= 18.

Hypericum mutilum

Hypericum tenuifolium

Phenology Flowering spring–mid summer (Apr–Jul).
Habitat Dry, sandy woods, dunes and dune hollows, coastal plain
Elevation 0–200 m (0–700 ft)
Distribution
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]
from FNA
AL; FL; GA; NC; SC
[WildflowerSearch map]
[BONAP county map]
Discussion

Subspecies 2 (2 in the flora).

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

Hypericum tenuifolium differs from H. galioides in habit, leaf size, and inflorescence, and in its drier habitat. Its nonrooting stems, longer leaves, and (usually) longer stems distinguish it from H. lloydii.

(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. 93. FNA vol. 6, p. 79.
Parent taxa Hypericaceae > Hypericum > sect. Brathys Hypericaceae > Hypericum > sect. Myriandra
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
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. 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. tetrapetalum, H. virgatum, H. ×mitchellianum
Subordinate taxa
H. mutilum subsp. latisepalum, H. mutilum subsp. mutilum
Synonyms Sarothra mutila H. fasciculatum var. laxifolium, H. reductum
Name authority Linnaeus: Sp. Pl. 2: 787. (1753) Pursh: Fl. Amer. Sept. 2: 377. (1813)
Web links