19. Flowers in spadices with a spathe forming sometimes a continuation of the stem. =19. Araceae.= Flowers not in spadices. 20 20. Stamen 1. Ovule 1, erect. Stigmas several. Flowers solitary or in glomerules in the axils of the leaves. _Naias_, =9. Naiadaceae=. Stamens 2-6. 21 21. Anthers turned outwards. Ovary with 1 ascending ovule in each cell and with several sessile stigmas. Flowers hermaphrodite. Seeds exalbuminous. _Triglochin_, =11. Scheuchzeriaceae=. Anthers turned inwards. Seeds albuminous. 22 22. Anthers 1-celled. Flowers unisexual, in spikelets usually arranged in spikes or panicles. Perianth dry. Stamens 2-3. Ovary with 1 pendulous ovule in each cell. =22. Restionaceae.= Anthers 2-celled. If flowers unisexual and in spikelets, then perianth not dry. 23 23. Flowers monoecious, in heads surrounded by an involucre. Ovary with 1 pendulous ovule in each cell. =25. Eriocaulaceae.= Flowers hermaphrodite, polygamous, or dioecious. 24 24. Style 1 with 3 long and thin stigmas. Perianth dry. Leaves linear. =31. Juncaceae.= Style 1 with 3 thick or short stigmas or with a single stigma, or styles 3. Perianth usually herbaceous. =32. Liliaceae.= 25. (17.) Perianth corolla-like. Usually ovules inverted and embryo or its radicle placed next to the hilum, more rarely ovules straight and embryo or its radicle remote from the hilum, and then albumen fleshy or cartilaginous. 26 Perianth differentiated into calyx and corolla. Ovules straight. Embryo small, remote from the hilum. Albumen more or less mealy. 31 26. Seeds with mealy albumen. 27 Seeds with fleshy or cartilaginous albumen. 29 27. Ovules 2 or more in each ovary-cell. Seeds with a large embryo enclosed in the albumen. =29. Pontederiaceae.= Ovule 1 in each ovary-cell. Seeds with a small embryo appressed to the albumen. Perianth white or yellow. 28 28. Perianth-segments free or nearly so. Anthers opening lengthwise. Stigmas 3. Fruit a berry. Stem climbing. Leaves scattered, ending in tendrils. Flowers in panicles. _Flagellaria_, =21. Flagellariaceae.= Perianth-segments united below into a tube. Anthers opening by apical pores. Stigma 1. Fruit a capsule. Stem erect. Leaves all radical. Flowers in heads. _Maschalocephalus_, =26. Rapateaceae.= 29. Stamens 3. Ovule 1 in each ovary-cell. Perianth yellow. =33. Haemodoraceae.= Stamens 6 or more, rarely 3, but then ovules 2 or more in each ovary-cell. 30 30. Anthers opening at the apex. Stamens affixed to the perianth. Ovary adnate to the perianth at the base. Ovules numerous in each cell. Perianth blue. Leaves linear or lanceolate. _Walleria_, =34. Amaryllidaceae.= Anthers opening lengthwise, rarely at the apex, but then stamens (at least some of them) and ovary free from the perianth. =32. Liliaceae.= 31. (25.) Ovary 2-3-celled. Fertile stamens 2-6. =28. Commelinaceae.= Ovary 1-celled, sometimes with incomplete partitions. Ovules numerous. Fertile stamens 3. Flowers in heads, short spikes, or umbels. 32