Perenial herb. Stems herbaceous, slender, 10-25(-70) cm long, simple or sometiomes branched, lower part elongate prostrate, and often rooted at nodes, then ascending, covered with articulate, crisp rusty hairs; internodes 3-10 mm long. Leaves sessile, lowest and middle opposite, narrowly elliptic, 4-8 × 1.5-2.75 mm, apex obtuse, base broadly cuneate, often somewhat auriculate and subamplexicaul, margins obviously recurved, subcoriaceous, glabrous and green above, brown beneath, sparsely covered with the same kind of hairs as stem, otherwise glabrous; midrib impressed adaxially, manifestly elevated beneath, lateral nerves invisible; uppermost leaves subverticillate, ovate, to 10 mm long, 4.5 mm wide, base subrounded. Flowers few (often 2-3), in uppermost, verticillately congested leaves. Pedicels less than 1 mm long. Calyx ca. 5 mm long, glabrous, divided almost to base, the lobes lanceolate, the apex acute. Corolla yellow, ca. 10 mm long, widely open; tube 1 mm long, the lobes obovate-elliptic, to 5 mm wide, apex rounded, dotted with minute, reddish glands. Filaments connate at base into a ring 0.5 mm long, the free parts about 1 mm long; anthers ca. 1.25 mm long, gradually narrowed from the cordate base. longitudinally dehiscent. Ovaries globose, glabrous. Styles to 3.5 mm long. Caspules ca. 2.5 mm in diam., brown, dehiscent into 5 valves. Flowers: May-Jun., fruits: Jul.-Aug.
HUALIEN: Chingshuishan, Leu, Lian & Sheng 1780 (Holotype!); Ho & Lien 1250 (Isotype!).
Endemic, known only from the exposed slope in the Chingshuishan, a metamorphosed limestone mountain, of Taroko National Park, very rare.
Lysimachia chingshuiensis is a very distinguished species in sect. Nummularia, somewhat similar to L. deltoideae Whight. in NE India, Sri Lanka, and SW China, but distinct by leaves subsessil, subcoriaceous, flowers congested at apices of stem and branches, congested in capinate inflorescences.
Phenology: perennial
Life form: herb
Root: rooting at node or not: rooting at node
Stem: present
Stem: type: prostrate at base, slender
Stem: shape: terete
Stem: indumentum: crisp rusty hairs
Leaf: position: cauline
Phyllotaxy: opposite
Leaf: petiole: sessile
Leaf: blade shape: elliptic
Leaf: blade apex: obtuse
Leaf: blade base: cuneate, subamplexicaul
Leaf: blade margin: entire
Leaf: blade surface: glabrous
Leaf: blade texture: coriaceous
Leaf: blade length (mm): 4-8
Leaf: blade width (mm): 1.5-2.75
Inflorescence: solitary
Inflorescence: position: terminal
Scape: absent
Peduncle: length (mm): 1
Bract: absent
Calyx: shape: 5-parted
Sepal: shape: lanceolate
Sepal: margin: entire
Sepal: length (mm): 3-5
Corolla: color: yellow
Corolla: shape: rotate
Lobe: margin: entire
Lobe: length (mm): 8-10
Lobe: width (mm): 3-5
Filament fused into a ring or not: filament fuse to a ring
Filament inserted position: base of corolla lobe
Filament: indumentum: glabrous
Filament and anther relative length: filament about equal to anther
Stamens protruding from corolla or not: Stamens protuding from corolla
Capsule: dehiscence type: longitudinal
Distribution: limestone mountain
