Description from Flora of China
Hypericum patulum Thunberg var. forrestii Chittenden, J. Roy. Hort. Soc. 48: 234. 1923; H. patulum f. forrestii (Chittenden) Rehder.
Shrubs, 0.3-1.5 m tall, bushy; branches erect or somewhat spreading. Stems 4-angled and slightly ancipitous when young, soon terete; internodes 1-4.5(-6) cm, usually shorter than leaves. Leaves with petiole 0.5-2 mm, rather broad; blade lanceolate or triangular-ovate to ± broadly ovate, 2.5-3(-6) × 0.9-3.2(-3.5) cm, thickly papery, abaxially paler but not glaucous; laminar glands short streaks and dots; abaxial glands dense, especially near midvein; main lateral veins 4- or 5-paired, tertiary reticulation obscure or invisible; base broadly cuneate to rounded, apex obtuse to rounded or slightly retuse. Inflorescence 1- to ca. 20-flowered, from 1(or 2) nodes, nearly flat-topped; bracts lanceolate or ± leaflike, persistent. Pedicels 4-10 mm. Flowers (2.5-)3.5-6 cm in diam., ± deeply cupped; buds broadly ovoid, apex obtuse to rounded. Sepals erect, subequal to equal, ovate or ± broadly elliptic to subcircular, 6-9 × 3-8 mm; laminar glands lines, ± interrupted distally; margin entire or finely eroded-denticulate toward apex with margin often hyaline, apex rounded or rarely subapiculate. Petals golden yellow, broadly obovate, 1.8-3 × 1.1-2.5 cm, 3-3.5 × as long as sepals; margin entire or remotely glandular-subdenticulate; apiculus rounded. Stamen fascicles each with 40-65 stamens, longest 1-1.5 cm, 0.4-0.6 × as long as petals. Ovary broadly ovoid, (4.5-)6-8 × 4-4.5 mm; styles 4-7 mm, 0.7-0.9(-1) × as long as ovary, free, suberect, outcurved near apex. Capsule ± broadly ovoid, 1.2-1.8 × 0.8-1.4 cm. Seeds dark reddish brown, 1.2-1.7 mm, distally slightly carinate or winged; testa scalariform-reticulate. Fl. May-Sep, fr. Aug-Oct. 2n = 36, 38.
Open stony situations on hillsides, sometimes beside streams, at Pinus forest margins; 1500-3000(-4000) m. WC Sichuan (Kangding, Tianquan), N and SW Yunnan [NE Myanmar].