1. Flowers without a spathe, regular. Perianth 3-parted. Stamen 1. Ovary 3-celled. Styles 3. Leaves undivided.--Species 5. Tropical and South Africa. (Plate 57.) [Tribe TRISTICHEAE.] =Tristicha= Thouars Flowers at first enclosed in a spathe, irregular. Perianth of 2, rarely of 3 small scales. Stamens 2-4. Ovary 1-2-celled. Styles 1-2. Leaves usually dissected. 2 2. Style 1, very short; stigma entire. Ovary 1-celled. Stamens 3-4; filaments free or nearly so. Stem elongate. Spathe close to the flower.--Species 1. Southern West Africa (Angola). [Tribe MARATHREAE.] =Angolaea= Wedd. Styles 2, free or united at the base. Stamens 2, rarely (_Winklerella_) 3, but then filaments united about halfway up. [Tribe PODOSTEMONEAE.] 3 3. Filaments free or nearly so. Ovary stalked. 4 Filaments obviously united. 5 4. Fruit with unequal valves, the persistent valve 5-nerved, the deciduous one 3-nerved. Stem little branched. Leaves linear or the lower with two teeth at the base.--Species 1. West Africa (Cameroons). =Ledermanniella= Engl. Fruit with two equal, persistent, linear, 5-nerved valves. Stem much branched. Leaves divided in 2-5 narrow segments.--Species 2. West Africa. Used as salad. =Dicraeanthus= Engl. 5. Ovary and fruit 1-celled, the latter with somewhat unequal valves. Flowers drooping.--Species 4. Central and South Africa. Used as salad. (Including _Isothylax_ Baill.) =Sphaerothylax= Bisch. Ovary and fruit 2-celled. 6 6. Fruit with unequal valves, one of which falls off, and with prominent ribs. Pollen-grains united in pairs.--Species 1. Madagascar. =Podostemon= Mich. Fruit with equal valves. 7 7. Fruit smooth, without distinct ribs. Pollen-grains separate. Flowers drooping.--Species 3. Southern Central Africa. (_Leiocarpodicraea_ Engl., under _Dicraea_ Thouars). =Leiothylax= Warm. Fruit with prominent ribs. 8 8. Fruit 2-toothed at the top, with boat-shaped valves, one of them or both falling off. Pollen-grains separate.--Species 1. West Africa (Cameroons). =Winklerella= Engl. Fruit with persistent valves. Pollen-grains united in pairs.--Species 9. Tropics. (Under _Podostemon_ Mich.) =Dicraea= Thouars FAMILY 94. HYDROSTACHYACEAE Aquatic herbs. Stem tuberous. Leaves with a sheath and a ligule. Flowers in spikes, bracteate, without a perianth, dioecious. Stamen 1, with separated anther-halves (or 2 with united filaments), hypogynous. Anthers turned outwards. Pollen-grains united in groups of 4. Ovary 1-celled, with 2 parietal placentas. Ovules numerous, inverted. Styles 2. Fruit capsular. Seeds exalbuminous. (Under _PODOSTEMONACEAE_.) (Plate 58.) Genus 1, species 15. Tropical and South-east Africa. =Hydrostachys= Thouars SUBORDER SAXIFRAGINEAE FAMILY 95. CRASSULACEAE