兰氏萍 lan shi ping

Lemna punctata G. Meyer, Prim. Fl. Esseq. 262. 1818; L. oligorrhiza Kurz; Spirodela oligorrhiza (Kurz) Hegelmaier; S. punctata (G. Meyer) C. H. Thompson; S. sichuanensis M. G. Liu & K. M. Xie.

Fronds obovate to elliptic, 1.5-8 mm, 1.5-3 × as long as wide, flat or gibbous, usually with papillae on upper surface along midvein. Roots (1 or)2-7(-12), all perforating scale, 0.5-7 cm. Turions not seen. Ovary with 1 or 2 ovules. Fruit laterally winged toward apex. Seed with 10-15 distinct ribs. Fl. (rare) Jun-Sep. 2n = 40*, 46, 50.

Ponds, lakesides, pools, ditches; in regions with mild winters and not very hot summers; sea level to 2400 m. Fujian, Henan, Hubei, Sichuan, Taiwan, Xizang, Yunnan, Zhejiang [India, Indonesia, Japan, Malaysia, Philippines, Thailand, Vietnam; Africa, Australia, North and South America, Pacific islands].

Spirodela sichuanensis was thought to be distinct from Landoltia punctata (as S. punctata) by its utricular scale surrounding the flower having two lateral slits instead of one as in L. punctata. However, two slits can be occasionally observed from various geographical races of L. punctata. Due to the rarity of flowering, the frequency of this character is hard to estimate. In general, all the vegetative characters of S. sichuanensis are included in the range of morphological variation of L. punctata.