Description from Flora of China
Epimedium platypetalum var. tenue B. L. Guo & P. K. Hsiao.
Herbs, 10-25 cm tall. Rhizome stout, irregularly nodose. Leaves basal and cauline, trifoliolate; petioles pilose with long reddish hairs forming conspicuous tufts at nodes; leaflets adaxially deep green, broadly ovate to suborbicular, 2-4 × 1.6-3 cm, abaxially papillose and sparsely pilose, adaxially glabrous, base deeply cordate with subequal lobes rounded and nearly touching, terminal leaflet similar to lateral leaflets in shape, margin spinose-serrate, apex rounded or acute. Flowering stem with 1 trifoliolate leaf. Raceme simple, 4-8 cm, 2-8-flowered. Pedicel 5-10 mm, slender, glandular pubescent. Flowers pale yellow, campanulate. Outer sepals triangular-lanceolate, 2-2.5 × ca. 0.7 mm; inner sepals broadly ovate, 4-5 × 2.5-3 mm, apically acute or shortly acuminate. Petals oblong or obovate-oblong, ca. 8 × 4-5 mm, flat, without spur, apex rounded. Stamens ca. 3 mm; filaments ca. 1 mm; anthers ca. 2 mm. Pistil ca. 4 mm. Capsules 1-2 cm; style 2-3 mm. Fl. Apr-May, fr. May-Jun.
● Forests; 1600-2800 m. Shaanxi, Sichuan.