Tristicha.] ex. poDOSTEMACEiE (baker and weight). 121 



Capsule not compressed, ribbed. 

 Valves of capsule equal. 



Ovary sessile ...... 5. DiCR^A. 



Ovary stipitate 6. Dicr^anthus. 



Valves of capsule unequal . . . .7. SPHiEROTHYLAX. 

 Flowers dioecious ; perianth none . . . .8. Hydrostachys. 



1. TKISTICHA, Thouars; Benth. et Hook. f. Gen. PI. iii. 108. 



Flowers hermaphrodite. Perianth membranous, 3-partite; seg- 

 ments oblong, obtuse, slightly imbricate. Stamen 1, hypogynous; 

 filament long ; anthers oblong. Ovary oblong, 3-celled ; styles 3, short, 

 linear ; stigmas decurrent on the inner side of the styles ; placentas 

 axile ; ovules numerous. Capsule oblong, crustaceous, septicidally and 

 septifragally 3-valved.— Herbs with a moss-like habit, growing under 

 water and attached to rocks by a flat lobed thallus. Stem slender, much- 

 branched. Leaves small, sessile, entire, pellucid, 1 -nerved. Flowers 

 terminal or axillary ; pedicels stiffly erect, each with 3 bracts at the 

 base. 



Species 3, variable and difficult of limitation. Also in South Africa, the 

 Mascarene Islands and Tropical America. 

 Leaves ovate-rotundate to ovate-oblong. 



Flowers axillary 1. T. trifaria. 



Flowers terminating short branches . . . 2. T. hypnoides. 

 Leaves oblong-linear . . . . . . 3. T. alternifolia. 



1. T. trifaria, Tulame in Ann. Sci. Nat, 3""^ ser. xi. 111. A much- 

 branched herb. Stems up to 9 in. long, at first erect, at length floating ; 

 leafy branches 6-9 lin. long. Leaves tristichous, ovate-rotundate to 

 ovate-oblong, very obtuse, imbricate, about 1 lin. long. Flowers soli- 

 tary, axillary, or terminal on short branches ; pedicel about 1 lin. long, 

 increasing to 5 lin. in fruit, slender, terete, rigid, glabrous. Perianth 

 marcescent ; lobes 3, slightly united at the base, ovate, acute, equal, 

 glabrous, patent, imbricate in bud. Filament flat; anthers ovoid. 

 Ovary obovoid-trigonous ; stigmas 3, equal, short, linear, at first erect, 

 finally recurved. Capsule 1 lin. long, obovoid-ellipsoid, obtuse, crowned 

 by the withered styles, faintly 9-ribbed. — Tulasne in Arch. Mus. Hist. 

 Nat. Par. vi. (1852), 180 ; Wedd. in DC. Prodr. xvii. 45 ; Warming in 

 Kgl. Danske Vidensk. Selsk. Skrifter, ser. 6, xi. i. 28, fig. 24 ; Hiern in 

 Cat. Afr. PI. Welw. i. 907. Dufourea trifaria, Bory ex Willd. Sp. PI. 

 V. 55. D. Boryi, A. Rich, in Diet. Class. Hist. Nat. v. 637. Cnjpto- 

 carpa tristicha, Tayl. ex Tulasne in Arch. Mus. Hist. Nat. Par. vi. 380. 



Xiower Guinea. Angola : Pungo Andongo j in the Praesidium, attached to 

 submerged rocks in the .Casalale stream, Welwitsch, 528 ! 

 Also in the Mascarene Islands. 



2. T. hypnoides, Spreng. Syst. iv. Cur. Post. 10. Stems csespi- 

 tose, often very short, branched, more or less compressed. Leaves 



