A key is provided to aid in the identification of the ten species of Lysimachia indigenous to Taiwan. Recently, in our botanical inventory of Taiwan we discovered on the summit of Chingshuishan, a metamorphosed limestone mountain in Taroko National Park, an additional species heretofore unknown to science, which is described here. Wight subsimilis, sed foliis sessilibus, subcoriaceis, floribus ad apicem caulium ramorumque in inflorescentias capitulatis congestis valde diversa. Stems herbaceous, covered with articulate, crisp, rusty hairs. Lower stems stoloniferous, slender, elongate prostrate, to 60 cm long, with diminutive leaves ca.
Flowers subsessile, solitary in the axils of the uppermost leaves.
Pedicel less than 1 mm long. 5 mm long, appressed pubescent mainly along midrib abaxially, divided almost to base, lobes lanceolate, apex acute. Corolla yellow, ca. Filaments connate at base into a ring, ring 0.5 mm long, free part ca. 1.25 mm long, longitudinally dehiscent.