Ascyrum villosum Linnaeus; Brathys tomentosa Spach; Hypericum pilosum Walter; H. villosum (Linnaeus) Crantz

Herbs annual or perennial, erect, usually unbranched proximal to inflorescence, 2–8 dm. Stems: internodes 4-lined, <scabrous-tomentose to pilose>. Leaves appressed to ascending, sessile; blade narrowly ovate or lanceolate to narrowly oblong-elliptic (or proximal oblanceolate), 4–15 × 1.5–7 mm, subcoriaceous, margins recurved, apex acute to obtuse, <surfaces scabrous-tomentose to pilose>, basal veins 1(–5), midrib with 0–1 pair of branches. Inflorescences cylindric to subcorymbiform, to 30-flowered, branching mostly dichasial. Flowers 5–11 mm diam.; sepals ovate to ovate-lanceolate or obovate, subequal, 2.5–5 × 1.5–2.5 mm, <margins setulose-ciliate>, apex acute; petals 5, deep yellow, obovate, 4–7 mm; stamens (15–)20–40, filaments almost distinct; styles 1.5–2 mm; stigmas ± broadly capitate. Capsules ovoid to ellipsoid-subglobose, 3.5–5 × 2–3 mm. Seeds 0.4–0.6 mm; testa linear-reticulate. 2n = 12.

Flowering early–late summer (Jun–Sep). Wet ditches, bogs, savannas, wet pinelands on sandy soil; 0–200 m; Ala., Fla., Ga., La., Miss., N.C., S.C., Tex., Va.

Hypericum setosum is the only American Hypericum sp. with an indumentum. It is related to H. virgatum (H. denticulatum subsp. acutifolium); in addition to having the indumentum, it is generally smaller and less branched and has a different chromosome number.