Contr. Gray Herb. 189: 21. 1962.
Shrubs, erect, sparsely branched, forming dense clumps sometimes with prop roots, to 40 dm, bark smooth and metallic-silvery, without laticifers, exfoliating in thin, curled plates. Stems: internodes 4-lined at first, soon 4-angled, then terete, dull silvery, glaucous. Leaf blades linear-subulate to acicular, (9–)12–17 × 0.5–0.8 mm, glaucous, base articulated, parallel or almost so, margins revolute, apex obtuse to rounded, midrib unbranched. Inflorescences narrowly cylindric, 1–3-flowered, usually with paired flowers or triads from to 9 proximal nodes. Flowers 20 mm diam.; sepals deciduous, not enclosing capsule, 5, linear-subulate, subequal, 7–8 × 0.5–0.8 mm, glaucous; petals 5, bright yellow, obovate-spatulate, 10–12 mm; stamens deciduous, 170–220; ovary 3-merous; styles 5 mm. Capsules narrowly ovoid to ellipsoid, 6–7 × 2.5–3.5 mm. Seeds narrowly carinate, 1–1.6 mm; testa coarsely reticulate-sulcate. 2n = 18.
Phenology: Flowering summer–early fall (Jun–Oct).
Habitat: Pond and lake margins to 1.5 m deep water
Elevation: 0–10 m
Of conservation concern.
Hypericum lissophloeus is found in Bay and Washington counties. The larger capsules, one- to three-flowered, lateral inflorescence branches, and smooth-polished, metallic bark (that exfoliates like that of Betula species) are among the features that distinguish H. lissophloeus from H. fasciculatum, H. nitidum, and their allies (H. brachyphyllum and H. chapmanii).