Description from Flora of China
Hypericum electrocarpum Maximowicz; H. esquirolii H. Léveillé.
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.
Hance and apparently all succeeding authors placed this species in Hypericum sect. Drosocarpium Spach o n the basis of its vesicular-gland-dotted capsule valves, despite its wide morphological and geographic differences from all species in that mainly SE European section. Disregarding its specialization, H. sampsonii and the closely related H. assamicum S. N. Biswas from NE India are morphologically a development from H. przewalskii. ..... The combination of perfoliate leaf pairs and vesicular-glandular capsule valves is confined to H. sect. Sampsonia.
Thickets, streamsides, grassy places, roadsides and cultivated margins; 100-1700 m. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Sichuan, Taiwan, Yunnan, Zhejiang [S Japan, E Myanmar, N Vietnam].