436 - SYSTEMATIC REVISION OF THE GENUS NAJAS, 



196. Loiigitudiual section of apex of root, showing root-cap. x 30. 



197. Male flower, x 25. 



198. Pollen-grains, showing spherical and oblong forms. Much enlarged. 



199. Female flower, x 12. 



200. Seed, x 12. 



201. Fossil seed from pleistocene, West Wittering, Sussex {Reid), x 12, 



202. Seed of var. angnstifolia. x 12. 



