Herbs, perennial, 20-80 cm tall, erect from decumbent rooting base; stems single or few, branched above or nearly throughout; branches curved-ascending. Stems terete, eglandular. Leaves in perfoliate pairs; blade broadly or narrowly lanceolate to oblong or oblanceolate, (2-)2.5-7(-8) × (0.7-)1-3.5 cm, thickly papery, abaxially paler, not glaucous; laminar gland dots all pale to mostly black, dense; intramarginal glands black, dense; main lateral veins 4- or 5-paired, tertiary reticulation rather lax; common base somewhat expanded, rounded, apex obtuse to rounded. Inflorescence 20-40-flowered from 2 nodes, flat-topped; flowering branches from up to 6 nodes below, the whole flat-topped to subpyramidal or cylindric; uppermost bract pair and bracteoles deciduous, and linear-lanceolate to linear, other bracts persistent, leaflike, margin entire. Flowers 6-10(-15) mm in diam., substellate with cupped base; buds ovoid, apex obtuse. Sepals free, erect, unequal, oblong to oblong-spatulate or linear-oblong, 3-7(-10) × 1-3 mm; laminar glands ± numerous, pale and rarely black, streaks to dots; intramarginal glands black, irregular, or rarely absent, margin entire, apex rounded; veins (3 or)5. Petals bright yellow, elliptic-oblong, 4-8(-13) × 1.5-4(-7) mm; laminar glands pale (very rarely a few black), short streaks to dots; marginal glands black, sessile or subsessile; margin entire or subentire. Stamens 30-42, apparently 3-fascicled, longest (2-)3-4(-6) mm, ca. 1/2 as long as petals. Ovary ovoid to narrowly pyramidal; styles 3, ca. 2 mm, ca. 0.65 × as long as ovary, outcurving. Capsule broadly ovoid to broadly or narrowly ovoid-pyramidal, 6-9 × 4-5 mm, exceeding sepals; valves with scattered ovoid to ± elongate amber vesicular glands. Seeds orange-brown, ca. 1 mm; testa finely ribbed-scalariform. Fl. May-Jul, fr. Jun-Oct.