31. Ovules 6 or more, parietal. Stamens 3-4. Leaves sagittate or hastate.--Species 2. North Africa. Poisonous and sometimes used as ornamental plants. The tubers are edible when cooked and yield starch; they are also used in medicine and as a substitute for soap. =Arum= L. Ovules 1-4, basal. Stamens 1-2. Leaves linear, oblong, ovate, or dissected. 32 32. Ovule 1. Leaves several, entire.--Species 3. North Africa. Used as ornamental plants. The tubers are edible when cooked, and yield starch, medicaments, and a substitute for soap. =Biarum= Schott Ovules 2-4. Leaf 1, dissected.--Species 2. East Africa and Angola. Used as ornamental plants. The tubers are edible when cooked, and yield starch, medicaments, and a substitute for soap. =Sauromatum= Schott FAMILY 20. LEMNACEAE Floating herbs without distinct stems or leaves, consisting of leaf-or grain-like fronds. Inflorescence seated in a cavity of the frond and consisting of 1-2 male flowers and a female. Flowers monoecious, without a perianth. Stamen 1. Ovary 1-celled, with 1-6 basal ovules and a funnel-shaped stigma. Seed-coat fleshy.--Genera 3, species 12. 1. Fronds rootless. Inflorescence on the back of the frond, without a spathe and consisting of 1 male and 1 female flower.--Species 6. (Including _Wolffiella_ Hegelm., under _Lemna_ L.) [Subfamily =WOLFFIOIDEAE=.] =Wolffia= Horkel Fronds with roots. Inflorescence at the margin of the frond, consisting of 2 male and a female flower enclosed by a spathe. [Subfamily =LEMNOIDEAE=.] 2 2. Fronds with one root each, 3-5-nerved.--Species 5. Some are used in medicine. “Duckweed.” =Lemna= L. Fronds with several roots each, many-nerved.--Species 1. (Under _Lemna_ L.) =Spirodela= Schleid. ORDER FARINOSAE SUBORDER FLAGELLARIINEAE FAMILY 21. FLAGELLARIACEAE Climbing herbs. Leaves lanceolate, ending in a tendril. Flowers in panicles, regular, hermaphrodite. Perianth-segments 6, free, subpetaloid, yellowish or whitish, the outer somewhat shorter than the inner. Stamens 6. Anthers turned inwards. Ovary superior, 3-celled, with a solitary, inverted ovule in the inner angle of each cell. Style with 3 linear, recurved stigmas. Fruit a 1-2-seeded berry. Seeds with a mealy albumen and a small marginal embryo. Genus 1. Species 1. Tropical and South-east Africa. Used in medicine and for plaiting-work. =Flagellaria= L. SUBORDER ENANTIOBLASTAE FAMILY 22. RESTIONACEAE Grass-like herbs. Leaves linear or reduced to the sheath. Flowers in spikelets usually arranged in spikes or panicles, regular, unisexual. Perianth of 3-6 membranous or scarious segments, imbricate in bud, rarely absent in the female flowers. Stamens 2-3. Anthers 1-celled. Ovary superior, 1-3-celled, with 1-3 pendulous, straight ovules. Fruit dry. Seeds with a mealy albumen and a marginal embryo.--Genera 12. Species 230. South Africa to Nyasaland. (Plate 13.) 1. Ovary 1-celled, sometimes 2-3-celled when young. Fruit 1-celled, indehiscent. 2