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Atlantic St. John's-wort

Habit Shrubs, usually decumbent, not rooting, forming mats, 1–5 dm. Herbs annual or perennial, erect or decumbent at base, not rooting, branches basal, relatively few or none, 1–7 dm.
Stems

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

internodes 4-angled.

Leaves

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.

erect to spreading, sessile;

blade linear-oblong or linear-lanceolate to linear, 5–33 × 0.5–2 mm, leathery, margins plane to revolute, apex acute, basal veins 1(–3), midrib with (0–)1–3 pairs of branches.

Inflorescences

± 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.

narrowly V-shaped, 1–50-flowered, branching mostly dichasial.

Flowers

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.

10–15 mm diam.;

sepals narrowly oblong to narrowly lanceolate, subequal to unequal, 3–7 × 0.8–1.6 mm, margins sometimes ciliate, not setulose-ciliate, apex acute;

petals golden yellow to orange-yellow, red-tinged , oblanceolate to obovate, 6–10 mm;

stamens 35–50, irregularly 3-fascicled;

styles 2.5–5 mm;

stigmas broadly capitate.

Capsules

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

± narrowly ovoid-conic, 4–9 × 2–4 mm.

Seeds

scarcely carinate, 0.5 mm;

testa coarsely reticulate.

0.5–0.7 mm;

testa finely linear-scalariform.

2n

= 18.

Hypericum tenuifolium

Hypericum paucifolium

Phenology Flowering spring–mid summer (Apr–Jul). Flowering spring.
Habitat Dry, sandy woods, dunes and dune hollows, coastal plain Dry, grassy habitats, roadsides
Elevation 0–200 m (0–700 ft) 0–50 m (0–200 ft)
Distribution
from FNA
AL; FL; GA; NC; SC
[WildflowerSearch map]
[BONAP county map]
from FNA
TX; Mexico
Discussion

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.)

The relatively long styles distinguish Hypericum paucifolium from all other North American species of sect. Trigynobrathys.

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

Source FNA vol. 6, p. 79. FNA vol. 6, p. 95.
Parent taxa Hypericaceae > Hypericum > sect. Myriandra 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. 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
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. 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
Synonyms H. fasciculatum var. laxifolium, H. reductum
Name authority Pursh: Fl. Amer. Sept. 2: 377. (1813) S. Watson: Proc. Amer. Acad. Arts Sci. 25: 143. (1890)
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