Description from Flora of China
Hypericum monanthemum J. D. Hooker & Thomson ex Dyer var. brachypetalum Franchet.
Herbs, perennial, 0.05-0.35 m tall or long, decumbent from creeping and rooting base; stems ?solitary or clustered, often branched below inflorescence or lower; branches slender, spreading. Stems terete or 2-4(-6)-lined, eglandular or occasionally with few reddish glands on lines. Leaves sessile or to 2 mm petiolate; blade ovate to oblong or elliptic to obovate or oblanceolate, 0.4-2.4 × 0.2-1.7 cm, subpapery, abaxially paler or usually glaucous; laminar gland dots pale, small to medium, dense; intramarginal glands black or rarely pale, dense to spaced; main lateral veins 2-4-paired, tertiary reticulation dense; base cordate to rounded or cuneate, the upper often with black-glandular-ciliate auricles and sometimes also glandular-ciliate proximal margin, margin entire, apex rounded. Inflorescence 1-12-flowered, from 1(or 2) nodes, often with flowering branches from up to 4 nodes below, the whole nearly flat-topped; bracts and bracteoles narrowly elliptic or linear-lanceolate to linear, black-glandular-ciliate and -auriculate or more rarely entire and then either bracteose or reduced leaflike. Flowers 1-2 cm in diam., stellate; buds ovoid to broadly ellipsoid, apex obtuse to acute. Sepals free, erect, equal to subequal, ovate-lanceolate or elliptic to linear-lanceolate, 3.5-7 × 1-2.5 mm; laminar glands pale or often partly black, lines (with the black parts dots to usually streaks) to dots; marginal glands black, on cilia or sessile or absent, margin glandular-ciliate to entire, apex subacute to acute or rarely rounded; veins 5. Petals bright yellow, sometimes tinged red in bud, oblong-elliptic to oblanceolate, 6-10 × 2-4 mm, 1.2-2 × as long as sepals; laminar glands black streaks or absent; marginal glands absent or 1-4, black, apical and subapical, sessile or on apical cilium; margin entire or rarely with one apical glandular cilium. Stamens 12-30, apparently 3-fascicled, longest 4-7 mm, 0.65-0.85 × as long as petals. Ovary ovoid to ellipsoid; styles 3(or 4), 2-3 mm, 0.65-1(-?1.3) × as long as ovary, divergent. Capsule ± broadly ellipsoid, 3-9 × 2.5-6 mm, 1.5-2 × as long as sepals. Seeds yellowish brown, 0.5-0.6 mm; testa densely scalariform-foveolate. Fl. Jun-Aug, fr. Aug-Oct.
The specimens of Hypericum himalaicum that most closely re semble H. trigonum , especially the intermediate population of that species from SE Xizang and N Myanmar, are found in C Nepal. The Chinese populations represent an eastward reduction trend from there that penetrates into Xizang through the Yadong (Chomo) gap and continues to NW Yunnan and north into Sichuan, where it has been known as H. monanthemum var. brachypetalum and where the sepals are sometimes apically entire and rounded.
Forest and woodland clearings, alpine meadows, rocky or grassy slopes, often in damp places; 2500-3300 m. SW Sichuan, SE Xizang, NW Yunnan [E Bhutan, N India, Nepal, Pakistan].