7. Perianth in the male flowers none, in the female cup-shaped and undivided. Anthers stalked, opening by 2 longitudinal slits. Carpels usually 4, slightly curved, with a peltate stigma.--Species 1. North and South Africa, southern West Africa, Madagascar and neighbouring islands. =Zannichellia= Mich. Perianth in the male flowers 3-toothed, in the female consisting of 1-3 segments. Anthers sessile, opening with one longitudinal slit. Carpels 3, straight, with a funnel-shaped stigma.--Species 1. North-west Africa (Algeria). =Althenia= Fr. Petit [Illustration: APONOGETONACEAE. _FLOW. PL. AFR._ _Pl. 5._ J. Fleischmann del. Aponogeton leptostachyus E. Mey. _A_ Plant in flower. _B_ Female flower. _C_ Carpel cut lengthwise.] [Illustration: ALISMATACEAE _FLOW. PL. AFR._ _Pl. 6._ J. Fleischmann del. Limnophyton obtusifolium (L.) Miq. _A_ Plant in flower. _B_ Male flower from above. _C_ Male flower cut lengthwise.] FAMILY 9. NAIADACEAE Herbs growing in fresh or brackish water. Leaves linear, toothed or spiny. Flowers axillary, solitary or in glomerules, unisexual. Perianth little developed, in the male flowers simple or double, sack-like, in the female simple and sack-like or wanting. Stamen 1. Anthers 1-or 4-celled. Pollen-grains globular or ovoid. Ovary 1-celled. Ovule 1, erect, inverted. Style 1; stigmas 2-3. Seed with a hard coat, exalbuminous. Embryo straight, with a large radicle and a well developed plumule. Genus 1, species 10. (Including _Caulinia_ A. Braun) =Naias= L. FAMILY 10. APONOGETONACEAE Aquatic herbs with a tuberous root-stock. Leaves radical, narrow, with several longitudinal and many transverse nerves. Flowers in 1-4 spikes connected at the base, enclosed when young in a sheath, and rising above the water. Perianth of 1-3 more or less brightly coloured segments. Stamens 6 or more, hypogynous, free. Anthers attached by the base, opening with two longitudinal slits. Carpels 3-8, distinct. Ovules in each carpel 2-8, basal or sutural, ascending, inverted. Fruits membranous, dehiscent. Seeds 2 or more, erect, exalbuminous, with a straight embryo. (Under _NAIADACEAE_.) (Plate 5.) Genus 1, species 20. Tropical and South Africa. Some are used as ornamental plants, especially the lattice-leaf (_A. fenestralis_ Hook. fil.) with perforated leaves. The tubers are edible and contain starch. (Including _Ouvirandra_ Thouars). =Aponogeton= Thunb. FAMILY 11. SCHEUCHZERIACEAE Marsh herbs. Leaves linear, with axillary scales. Flowers in terminal racemes or spikes, regular, hermaphrodite. Perianth of 6 segments, usually green. Stamens 3-6. Anthers turned outwards; pollen-grains ovoid. Ovary 3-6-celled. Ovule 1 in each cell, ascending, inverted. Stigmas sessile. Seeds exalbuminous, with a straight embryo. (_JUNCAGINEAE_, under _NAIADACEAE_.) Genus 1, species 4. North, South, and West Africa. The leaves and fruits of some species are edible. (_Juncago_ Tourn.) =Triglochin= L. SUBORDER ALISMATINEAE FAMILY 12. ALISMATACEAE