Ovary almost superior. Stamens equal. Flowers blue, with bracteoles, solitary or in pairs and axillary, or arranged in panicles. Leaves scattered along the stem.--Species 5. Southern tropical Africa. Some have edible root-stocks. =Walleria= Kirk FAMILY 35. VELLOZIACEAE Leaves linear. Flowers solitary, terminal, without bracteoles, regular, hermaphrodite. Perianth-segments free or nearly so, petaloid, usually white. Stamens 6. Anthers attached by the base. Ovary inferior, 3-celled. Placentas projecting and peltately dilated. Ovules numerous. Style simple; stigma 3-lobed. Fruit a capsule. Seeds black, compressed. Embryo very small, enclosed by the albumen. (Under _AMARYLLIDEAE_.) (Plate 20.) Genus 1. Species 25. Tropical and South Africa. (_Xerophyta_ Juss., under _Vellozia_ Vand.) =Barbacenia= Vand. FAMILY 36. TACCACEAE Herbs with a tuberous root-stock. Leaves all radical, large, stalked, twice pinnately divided. Flowers in an umbel-like inflorescence on a leafless scape, regular, hermaphrodite. Perianth greenish-brown, bell-or urn-shaped, with a short tube. Stamens 6. Filaments hooded. Anthers turned inwards. Ovary inferior, 1-celled, with parietal placentas. Ovules numerous, inverted. Style short, umbrella-shaped, 6-lobed. Fruit a berry. Seeds compressed. Embryo small, enclosed by the albumen. Genus 1, species 2. Tropics. Used as ornamental plants and for plaiting-work; the tubers yield starch (arrowroot) and are edible when cooked. =Tacca= Forst. FAMILY 37. DIOSCOREACEAE Root-stock tuberous. Stem twining. Leaves alternate, net-veined, usually cordate. Flowers in racemes, inconspicuous, regular, unisexual. Stamens 6. Ovary inferior, 3-celled. Ovules 2 in each cell, superposed, inverted. Styles or style-branches 3. Embryo enclosed in a horny or cartilaginous albumen.--Genera 2, species 45. (Plate 21.) Fruit a berry. Seeds not winged.--Species 3. North Africa. The tubers are eaten and used in medicine; the berries are poisonous. (_Tamnus_ Juss.) =Tamus= L. Fruit a capsule. Seeds winged.--Species 40. Tropical and South Africa. Some are cultivated for their edible tubers (yams) or used in medicine; others are poisonous. (Including _Testudinaria_ Salisb.) (Plate 21.) =Dioscorea= L. SUBORDER IRIDINEAE FAMILY 38. IRIDACEAE Herbs or undershrubs. Inflorescence terminal. Flowers hermaphrodite. Perianth with 6 petaloid segments. Stamens 3, inserted opposite the outer perianth-segments. Anthers turned outwards. Ovary inferior, 3-celled, rarely (_Hermodactylus_) 1-celled. Style-branches usually divided or dilated. Ovules numerous, inverted. Fruit a loculicidal capsule. Embryo enclosed by the horny albumen.--Genera 39, species 600. (Plate 22.) 1. Flowers solitary, terminal, sometimes surrounded by several axillary flowers, each flower with a spathe. Perianth regular; inner and outer segments nearly equal. Leaves not exactly 2-ranked. Stem short or almost wanting. [Subfamily =CROCOIDEAE=.] 2