Male flowers somewhat irregular, with 2-3 fertile stamens and sometimes a sterile one. Stigmas ovate, notched or two-toothed. Leaves several-nerved.--Species 2. North and Central Africa. Used in refining sugar. =Vallisneria= Mich. 6. Leaves in two rows. Ovules inverted, inserted in the angles formed by the placentas and the wall of the ovary. Radicle of the embryo strongly developed. Marine plants. [Subfamily =THALASSIOIDEAE=.] 7 Leaves in rosettes. Ovules inverted, but inserted on the whole surface of the placentas, or straight. Radicle of the embryo not strongly developed. Freshwater plants. [Subfamily =STRATIOTOIDEAE=.] 8 7. Scape of the male flowers short, of the female long and at length spirally twisted. Male spathes several-flowered; flowers with 3 petals and 3 stamens.--Species 1. Madagascar and Red Sea. Yields fibres and edible seeds. =Enalus= L. C. Rich. Scapes moderately long, not spirally twisted. Male spathes one-flowered; flowers without petals, with 6 stamens.--Species 1. East Africa. =Thalassia= Soland. 8. Placentas undivided. Ovules straight. Fertile stamens 9. Stem emitting runners. Leaves floating.--Species 1. Algeria and Madagascar. “Frogbit.” [Tribe HYDROCHARITEAE.] =Hydrocharis= L. Placentas two-cleft. Ovules inverted. Seeds very numerous. Fertile stamens 6-12. Stem very short, without runners. Leaves at least partially submerged. [Tribe OTTELIEAE.] 9 9. Flowers hermaphrodite. Spathes one-flowered. Stigmas 6.--Species 9. Tropics and Egypt. Some are used as vegetables. (Plate 7.) =Ottelia= Pers. Flowers dioecious. Spathes of the male flowers several-flowered. Stigmas 9-15.--Species 10. Tropics. Some are used as vegetables. =Boottia= Wall. ORDER TRIURIDALES FAMILY 15. TRIURIDACEAE Small, pale, yellowish or reddish herbs. Leaves reduced to scales. Flowers in racemes, regular, monoecious. Perianth of 6 petaloid, valvate segments united at the base. Stamens 3; filaments short or wanting; anthers 2-celled, opening transversely. Carpels inserted on a convex or conical receptacle, [Illustration: HYDROCHARITACEAE. _FLOW. PL. AFR._ _Pl. 7._ J. Fleischmann del. Ottelia alismoides (L.) Pers. _A_ Plant in flower. _B_ Flower. _C_ Stamen. _D_ Pistil cut lengthwise.] [Illustration: GRAMINEAE. _FLOW. PL. AFR._ _Pl. 8._ J. Fleischmann del. Chloris Gayana Kunth _A_ Plant in flower. _B_ Inflorescence. _C_ Spikelet. _D_ Flower. _E_ Empty glume above the flower.] numerous, distinct; styles lateral; ovules solitary, erect, inverted. Fruits dehiscing by a longitudinal slit. Genus 1, species 3. West Africa and Seychelles. (Including _Seychellaria_ Hemsl.) =Sciaphila= Blume ORDER GLUMIFLORAE FAMILY 16. GRAMINEAE