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roundpod St. Johnswort

round-fruit St. John's-wort, roundseed St. Johnswort

Habit Shrubs, erect, unbranched or with relatively short branches and sometimes 1–2 branches ascending from proximal nodes, 5–13 dm. Herbs (perennial) or subshrubs, erect or decumbent, not or rarely rhizomatous, unbranched or branched proximally, 2–6 dm.
Stems

internodes 4-lined at first, then terete.

internodes 2–4-lined.

Leaf

blades narrowly oblong or narrowly elliptic-oblong to triangular-lanceolate, 15–40 × 2–10 mm, base not articulated, cuneate to subcordate, margins recurved, apex subacute to rounded, midrib with 1 pair of branches.

blades narrowly elliptic or narrowly oblong to linear, 30–70 × 3–15 mm, base not articulated, narrowly cuneate to linear, margins plane to revolute, apex subacute to rounded, midrib with 0–4 pairs of branches.

Inflorescences

corymbiform to cylindric, (7–)15–65-flowered, narrowly branched, sometimes with 3–65-flowered dichasia from 1–2 proximal nodes and relatively short, flowering branches from further 1–4 nodes.

rounded-corymbiform, 7–70-flowered, narrowly branched, sometimes with dichasia or branches from to 8 proximal nodes.

Flowers

7–12 mm diam.;

sepals persistent, not enclosing capsule, 5, obovate or broadly elliptic to oblong, unequal, 2–4 × 1–1.7 mm;

petals 5, bright yellow, oblanceolate, 5–8 mm;

stamens (some or all) persistent, 30–50;

ovary 3-merous, placentation parietal.

10–15 mm diam.;

sepals persistent, not enclosing capsule, 5, broadly ovate to oblong-elliptic, ± unequal, 2.5–5 × 1.5–3 mm;

petals 5, bright yellow, oblanceolate-elliptic to elliptic, 5–9 mm;

stamens persistent, 45–85;

ovary 3-merous, placentation parietal.

Capsules

ovoid-cylindric to broadly ovoid, 4–6 × 3–4 mm.

broadly ovoid to depressed-globose, 4.5–8 × 4–7 mm.

Seeds

not carinate, 0.6 mm;

testa reticulate to linear-foveolate.

carinate, 2–2.7 mm;

testa coarsely reticulate.

2n

= 18.

Hypericum cistifolium

Hypericum sphaerocarpum

Phenology Flowering spring–early fall (Apr–Oct). Flowering summer (Jun–Aug).
Habitat Pine flatwoods, margins of bogs, swamps, and marshes, ditches, on sand, coastal plain Rocky outcrops or embankments, prairies, stream banks, usually wet or moist, railroad embankments
Elevation 0–300 m (0–1000 ft) 500–1000 m (1600–3300 ft)
Distribution
from FNA
AL; FL; GA; LA; MS; NC; SC; TX
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from FNA
AL; AR; IA; IL; IN; KS; KY; MI; MO; MS; NE; OH; OK; TN; TX; WI; ON
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Discussion

Hypericum cistifolium is woodier in habit than H. sphaerocarpum and has shorter leaves, smaller flowers, narrower sepals, narrower capsules, and smaller seeds.

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

Hypericum sphaerocarpum differs from H. cistifolium and H. nudiflorum in its semiherbaceous habit and more northwestern distribution, as well as in its combination of relatively long, narrow leaves, persistent sepals, globose and apiculate to rounded capsules, and relatively large seeds. The narrow-leaved, bushy form from eastern parts of the range (var. turgidum) merges with the typical form.

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

Source FNA vol. 6, p. 82. FNA vol. 6, p. 83.
Parent taxa Hypericaceae > Hypericum > sect. Myriandra 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. 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. 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. suffruticosum, H. tenuifolium, H. tetrapetalum, H. virgatum, H. ×mitchellianum
Synonyms H. opacum, H. punctulosum, H. rosmarinifolium Brathydium chamaenerium, B. sphaerocarpum, H. chamaenerium, H. sphaerocarpum var. turgidum, H. turgidum
Name authority Lamarck: in J. Lamarck et al., Encycl. 4: 158. (1797) Michaux: Fl. Bor.-Amer. 2: 78. (1803)
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