680 SYSTEMATIC BOTANY. 



capsular, occasionally somewhat adherent to the persistent 

 perianth. Seeds numerous, with mealy albumen. 



Distribution, 8fc. — They are natives of the East Indies, 

 Africa, and America. Examples: — Leptanthus, Pontederia. 

 There are 6 genera, and 30 species. Their properties are 

 unimportant. 



Natural Order 263. Mayace^. — The Mayaca Order. — 

 Diagnosis. — Small moss-like plants growing in damp places. 

 They are closely allied to Commelynaceae, from which they 

 differ in habit, in their 1 -celled anthers, in their 1 -celled ovary 

 and capsule with parietal placentas, and in their carpels being 

 opposite to the inner segments of the perianth. 



Distribution, Sfc. — They are found in America from Brazil to 

 Virginia. Mayaca is the only genus, of which there are 4 

 species. Their properties and uses are unknown. 



Natural Order 264. Commelynace^. — The Spider-Wort 

 Order. — Herbs with flattened, narrow, usually sheathing leaves. 

 Perianth inferior, more or less irregular, in 6 parts arranged 

 in two whorls; the outer parts being green, persistent, and 

 opposite to the carpels ; the inner petaloid. Stamens 6 or 3, 

 some generally abortive, hypogynous ; an//jers2-celled. introrse. 

 Ovary 3-celled, superior; style 1. Capsule 2 — 3-celled, 2 — 

 3-valved, with loculicidal dehiscence and axile placentation. 

 Seeds few, with a linear hilum ; embryo shaped like a pulley, 

 remote from the hilum, in dense fleshy albumen. 



Distribution, Sfc. — They are chiefly natives of India, Africa, 

 Australia, and the West Indies. Examples : — Commelyna, 

 Tradescantia, Cyanotis, Flagellaria. There are 1 6 genera, and 

 260 species. 



Properties and Uses. — Their properties are unimportant. 

 The rhizomes of some species, as those of the Commelyna tuberosa, 

 angustifolia, and striata, contain much starch, and in a cooked 

 state are edible. Some species have been reputed astringent 

 and vulnerary, and others emmenagogue, &c.; but they re- 

 quire no particular notice from us. 



Natural Order 265. Xyridace^. — The Xyris Order.— 

 Sedge-like herbaceous plants. Leaves radical, sheathing, en- 

 siform or filiform. Flowers perfect, in scaly heads. Perianth 

 inferior, of 6 parts arranged in two whorls, — the outer gluma- 

 ccous, distinct, and opposite the carpels ; the inner petaloid, and 

 united. Stamens 6, 3 being fertile and inserted on the peta- 

 loid perianth; anthers extrorse. Ovary superior, 1- celled, with 

 parietal placentas. Capsule 1 -celled, 3-valved. Seeds nume- 

 rous, orthotropous ; embryo minute, on the outside of fleshy 

 albumen. 



Distribution, 8fc. — Exclusively natives of tropical and sub- 

 tropical regions. Examples :— Xyris, Rapatea. There are 5 

 genera, and 70 species. 



