Characters;"C. luzhijiangensis";"C. mekongensis";"C. cana";"C. pallida" "Stem length (cm)";10–30;20–30;15–30;"20–50 (–60)" "Stem indumentum";"densely white villous";"pilose to sparely villous";"densely white villous, sometimes tomentose";"hirsute to hispid" "Leaf scars at lower part of stem";numerous;absent;"absent or few";"absent or few" "Leaf shape";oblanceolate;"oblong, narrowly obovate or oblanceolate";"ovate, elliptic, oblanceolate or linear-lanceolate";"elliptic, rhombic-elliptic or oblong" "Leaf size (cm)";"0.3–2.0 × 0.1–0.3 (–0.5)";"0.5–3.0 × 0.3–1.2";"0.4–2.5 × 0.3–1.0";"1.0–4.0 × 0.3–1.5" "Leaf apex";"obtuse to acute";"usually acute, rarely obtuse";"obtuse to acute";"acute to acuminate" "Leaf margin";"subentire or sparsely crenate, slightly recurved";"serrate, not recurved";"subentire, crenulate, or serrate, slightly recurved";"denticulate or almost entire, not recurved" Flower;"erect or ascending, rarely reflexed";"ascending to nodding";"erect or ascending, sometimes pendent";"usually pendent" "Length of flower pedicel (cm)";0.5–1.0;"up to 2.0";0.5–3.0;0.4–2.0 Hypanthium;"obconic, externally spreading villous";"obconic or campanulate, only hispid along ribs";"obdeltoid to broadly obconical, externally villous to tomentose";"obconic or campanulate, externally hirsute to hispid" "Shape of calyx lobes";ovate;subulate;"subulate or narrowly triangular";"deltoid, narrowly triangular, or subulate" "Size of calyx lobes (mm)";"1–2 × 1.0–1.5";"2–4 mm long, less than 1 mm wide";"3–5 × 2–3";"2–8 × 2–5" "Length of corolla (mm)";5–10;8;10–15;4–15 "Diameter of corolla tube (mm)";2–4;6–10;2–7;5–10