Hypericum sphaerocarpum |
Hypericum tetrapetalum |
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round-fruit St. John's-wort, roundseed St. Johnswort |
fourpetal St. Johnswort |
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Habit | Herbs (perennial) or subshrubs, erect or decumbent, not or rarely rhizomatous, unbranched or branched proximally, 2–6 dm. | Herbs (perennial) or shrubs, erect, with woody base, usually unbranched, sometimes with divaricate or ascending branches, 2–10 dm. |
Stems | internodes 2–4-lined. |
internodes (2–)4-lined at first, then 2-lined to terete. |
Leaf | 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. |
blades oblong-ovate to ovate or triangular-ovate, 5–35 × 4–15 mm, base articulated, cordate-amplexicaul, margins subrecurved, apex apiculate or obtuse to rounded, midrib with 1 pair of branches. |
Inflorescences | rounded-corymbiform, 7–70-flowered, narrowly branched, sometimes with dichasia or branches from to 8 proximal nodes. |
terminal, 1(–3)-flowered, branching from apical node pseudodichotomous, sometimes with relatively short branches from to 3 proximal nodes. |
Flowers | 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. |
20–30 mm diam.; sepals persistent, enclosing capsule, 4, unequal, outer broadly ovate, 7–15 × 5.5–10 mm, apex subapiculate to obtuse, inner narrowly lanceolate, 7–15 × 2–3 mm, apex acute; petals 4, bright yellow, obovate-oblong, 10–15 mm; stamens persistent, 100; ovary 3-merous. |
Capsules | broadly ovoid to depressed-globose, 4.5–8 × 4–7 mm. |
broadly ellipsoid-ovoid to subglobose, 5–6 × 3.5–4 mm. |
Seeds | carinate, 2–2.7 mm; testa coarsely reticulate. |
not carinate, 0.7 mm; testa shallowly scalariform. |
2n | = 18. |
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Hypericum sphaerocarpum |
Hypericum tetrapetalum |
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Phenology | Flowering summer (Jun–Aug). | Flowering winter–spring (Jan–Apr), late summer (Jul–Sep). |
Habitat | Rocky outcrops or embankments, prairies, stream banks, usually wet or moist, railroad embankments | Moist, low pinelands, ditches |
Elevation | 500–1000 m (1600–3300 ft) | 0–200 m (0–700 ft) |
Distribution |
AL; AR; IA; IL; IN; KS; KY; MI; MO; MS; NE; OH; OK; TN; TX; WI; ON
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AL; FL; GA; West Indies (w Cuba)
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Discussion | 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.) |
Hypericum tetrapetalum differs from H. crux-andreae in having broader leaves with strongly cordate-amplexicaul bases and, nearly always, by terminal pseudodichotomous inflorescences. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 6, p. 83. | FNA vol. 6, p. 86. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Brathydium chamaenerium, B. sphaerocarpum, H. chamaenerium, H. sphaerocarpum var. turgidum, H. turgidum | Ascyrum amplexicaule, A. cubense, A. tetrapetalum |
Name authority | Michaux: Fl. Bor.-Amer. 2: 78. (1803) | Lamarck: in J. Lamarck et al., Encycl. 4: 153. (1797) |
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