ABSTRACT
Aquatic, free-floating plants. Rhizome horizontal, thread-like and highly branching, bearing alternate, imbricate leaves and pendulous, haplo-protostelic, chlorophyllous roots, solitary or in clusters. Leaves sessile, alternate and in two rows along the rhizome. Each leaf bilobed, with a fleshy chlorophyl lous dorsal lobe held proud of the water, (just above the water) and a thinner, translucent ventral lobe which floats on the water. Within mucilaginous cavi ties in the dorsal lobes are filaments of the cyanobacterium symbiont Anabaena azollae.
