WATER-PLAXTAIX FAMILY 509 



producing i — 3 flowers^ enclosed in a membranous spaihe, in a 

 marginal cleft ; stafnens stalked, with 2-chambered anthers. 

 (Name, the Greek name of the plant.) 



1. L. trisulca (Ivy-leaved Duck-weed). — Fronds thin, pellucid, 

 J — I in. long, budding at right angles, obovate-lanceolate, each 

 bearing i root. Bulbils are produced in autumn. — Stagnant 

 water : frequent. — Fl. June. Annual. 



2. L. minor (Lesser Duck-weed). — Fronds compressed, opaque, 

 paler beneath, not more than \ in. long, obovate, blunt, each 

 bearing 1 root. — Stagnant water ; often so abundant as to cover 

 the surface, where, with the insects which it harbours, it is greedily 

 devoured by ducks. — Fl. June — August. Annual. 



3. L. gibba (Gibbous Duck-weed). — Frofids flat above, hemi- 

 spherical and spongy beneath, opaque, pale, ^ — h in. long, 

 obovate, blunt, each bearing i root. — Stagnant water ; uncommon. 

 — Fl. June — September. Annual. 



LEMNA Mi NOR (Lcsser Duck-iueed). 



4. L. polyrrhiza (Greater Duck-weed). — Fronds dark green 

 above, purple beneath, compressed, ^ — I in. long, broadly 

 obovate, each bearing many clustered roots. — Ponds and ditches ; 

 not common. — Flower not known in Britain. Annual. 



2. WoLFFiA, represented by the one British species, IF. arrhiza, 

 is the smallest known flowering plant, the rootless, flattish, sub- 

 globular fronds not being more than ~ in. long. — Ponds near 

 London. The iiower is not known in Britain. Annual. 



Ord. LXXXVII. Alismace.^. — Water-Plantain Family ^ 



A small but widely distributed Order of aquatic plants, often 

 floating, with leaves chiefly radical, with long, sheathing stalks ; 

 -flowers usually perfect ; perianth of 6 distinct leaves in 2 whorls, 

 the 3 inner, or all, coloured ; stamens 6, 9, or more, hypogynous ; 



