Tristicha. | CX. PODOSTEMACE (BAKER AND WRIGHT). 121 
Capsule not compressed, ribbed. 
Valves of capsule equal. 
Ovary sessile . 5. DIcRma. 
Ovary stipitate : 6. DICREHEANTHUS. 
Valves of capsule unequal . 7. SPHEROTHYLAX. 
Flowers dicecious ; perianth none 8. HYDROSTACHYS. 
1, TRISTICHA, Thouars; Benth. et Hook. f. Gen. Pl. iii. 108. 
Flowers hermaphrodite. Perianth membranous, 3-partite; seg- 
ments oblong, obtuse, slightly imbricate. Stamen 1, hypogynous; 
filament long ; anthers obleng. 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.mHerbs 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 . z : 5 : . 1. f. trifaria, 
Flowers terminating short branches . j . 2. 7. hypnoides. 
Leaves oblong-linear : : : ; 3. TZ. alternifolia, 
1, 'T. trifaria, Tulasne in Ann. Sci. Nat. 3” sér. 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. Pl. Welw. i. 907. Dufourea trifaria, Bory ex Willd. Sp. PI. 
v.55. D, Boryi, A. Rich. in Dict. Class. Hist. Nat. v. 637. Crypto- 
carpa tristicha, Tay]. ex Tulasne in Arch. Mus. Hist. Nat. Par. vi. 180. 
Lower Guinea. Angola: Pungo Andongo; in the Presidium, 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 cespi- 
tose, often very short, branched, more or less compressed. Leaves 
