25. Hypericum tetrapetalum Lamarck in J. Lamarck et al., Encycl. 4: 153. 1797.
Ascyrum amplexicaule Michaux; A. cubense Grisebach; A. tetrapetalum (Lamarck) Vail
Herbs (perennial) or shrubs, erect, with woody base, usually unbranched, sometimes with divaricate or ascending branches, 2–10 dm. Stems: internodes (2–)4-lined at first, then 2-lined to terete. Leaf 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 <terminal>, 1(–3)-flowered, branching from apical node pseudodichotomous, sometimes with relatively short branches from to 3 proximal nodes. Flowers 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 ellipsoid-ovoid to subglobose, 5–6 × 3.5–4 mm. Seeds not carinate, 0.7 mm; testa shallowly scalariform. 2n = 18.
Flowering winter–spring (Jan–Apr), late summer (Jul–Sep). Moist, low pinelands, ditches; 0–200 m; Ala., Fla., Ga.; West Indies (w Cuba).
Hypericum tetrapetalum differs from H. crux-andreae in having broader leaves with strongly cordate-amplexicaul bases and, nearly always, by terminal pseudodichotomous inflorescences.