Embryo outside the albumen, at its base. Seed and ovule attached laterally, but often near the base, usually adnate to the pericarp or the wall of the ovary. Style 1, with 1-6 stigmas, or styles 2. Anthers usually affixed at the back. Sheaths of the leaves nearly always split on one side and ending in a ligule. Stem usually cylindrical and hollow between the nodes. =16. Gramineae.= 9. Plants without differentiation into stem and leaves, consisting of small floating leaf-or granule-like shoots. Flowers 2-3 together in cavities of the shoots =20. Lemnaceae.= Plants differentiated into stem and leaves 10 10. Flowers solitary or in glomerules in the axils of the leaves. Carpel solitary. _Naias_, =9. Naiadaceae=. Flowers in spikes, spadices, or heads, rarely (_Potamogetonaceae_) solitary or in glomerules, but then several separate carpels 11 11. Male flowers in panicles, female in heads or spadices. Flowers dioecious. Leaves narrow, usually serrate or prickly. Stem usually woody. _Pandanus_, =6. Pandanaceae=. Male or all flowers solitary or in spikes, heads, or cymes 12 12. Flowers in globose heads _Sparganium_, =7. Sparganiaceae=. Flowers solitary or in spikes, spadices, or cymes 13 13. Ovaries several, separate, rarely ovary solitary, and then marine plants, very rarely freshwater-plants with hermaphrodite flowers. If flowers in spadices or spikes, then hermaphrodite or polygamous with 1 or several one-ovuled ovaries =8. Potamogetonaceae.= Ovary solitary. Land-, marsh-, or freshwater-plants; the latter with unisexual flowers. Flowers in spadices, unisexual, rarely hermaphrodite, but then with a several-ovuled ovary. 14 14. Flowers monoecious; male inflorescence, at least when young, separated from the female by a deciduous spathe. Flowers usually surrounded by hairs. Ovule 1, pendulous. Seed-coat not fleshy. _Typha_, =5. Typhaceae=. Flowers hermaphrodite or unisexual; if monoecious, then male inflorescence in uninterrupted connexion with the female, or separated from it by an empty interval or by barren flowers, but not by a spathe. Seed-coat fleshy. =19. Araceae.= 15. (6.) Ovary superior. 16 Ovary inferior or half-inferior. 37 16. Carpel solitary or carpels connate and forming a single entire or slightly lobed ovary. 17 Carpels several, separate or cohering only at the base. 33 17. Perianth calyx-like, sometimes slightly coloured, but firmly membranous or leathery, or differentiated by size or coalescence into an inner and an outer whorl of segments, all of which are sepaloid. 18 Perianth corolla-like or consisting of outer sepaloid and inner petaloid segments. 25 18. Leaves folded in the bud, subsequently splitting into pinnately or palmately disposed segments, rarely only 2-cleft. Stem woody, but sometimes very short. Flowers in spadices or panicles with spathes. =18. Palmae.= Leaves undivided, rarely divided, but then not folded and springing from a herbaceous stem. 19