Triglocuin.] NAIADACEjE. 429 



or sheathing and inserted within the petiolar sheath. Flowers incon- 

 spicuous, 1-2-sexual, green. Perianth 0, or tubular, or cup-shaped, or of 

 3-4 inferior valvate segments. Stamens hypogynous ; anthers 1-2-celled. 

 Ovary of 1-4 carpels ; style 1, stigma various ; ovules one in each carpel, 

 rarely more, erect or pendulous. Fruit of one or more utricles achenes or 

 drupes. Seed solitary, testa membranous, albumen ; embryo straight or 

 curved, radicular end very large. — Distbib. All climates ; genera 16 ; 

 species 120. — Affinities. With Alismacece. — Properties unimportant, 



Tribe I. JUNCAGIN'EiE. Erect marsh herbs, with rush-like leaves. 

 Floivers spiked or racemed, 1-2-sexual. Perianth-segments 3 or 6, herbaceous 

 Stamens 6. Carpels 3 or more ; ovules basilar, erect, anatropous. Embryo 

 straight. 



Flowers ebracteate. Anthers subsessile, short 1. Triglochin. 



Flowers bracteate. Filaments and anthers long 2. Scheuchzeria. 



Tribe II. POTAME'iE. Aquatic herbs. Flowers spiked, 2-sexual. Perianth- 

 segments 4, berbaceous, or 0. Stamens 2 or 4. Carpels 4 ; ovules solitary, 

 axile, campylotropous. Embryo curved. 



Perianth-segments 4. Achenes sessile 3. Potamogeton. 



Perianth 0. Achenes stipitate 4. Ruppia. 



Tribe III. ZANNICHELLIE'iE. Aquatic herbs. Flowers axillary, 1-sexual. 

 Perianth or hyaline. Stamen 1. Carpels 2-9 ; ovules solitary, pendu- 

 lous, orthotropous. Embryo induplicate or involute. 

 Perianth 5. Zannichellia. 



Tribe IV. ZOSTERE'ffi. Marine herbs. Flowers sessile on a flattened 



spadix, 1-sexual. Perianth 0. Anthers sessile, 1-celled, pollen confervoid. 



Carpels solitary, sessile ; ovules solitary, pendulous, orthotropous. Embryo 



straight with the cotyledonary end in a slit. 



Flowers monoecious 6. Zostera. 



Tribe V. NAIADE'iE. Aquatic herbs. Flowers axillary, solitary or 

 crowded. Perianth hyaline. Anther 1. Carpels solitary; ovules soli- 

 tary, basilar, anatropous. Embryo straight. 

 Perianth tubular 7. Naias. 



1. TRIGLO'CHIN, L. 



Boots fibrous. Leaves erect, very narrow. Flowers racemed, small, green, 

 ebracteate, anemophilous, proterogynous. Perianth-segments 6, all similar, 

 cucullate, subequal, deciduous. Stamens 6, on the base of the perianth- 

 segments, filaments very short ; anthers broad, extrorse. Ovary 6-celled ; 

 stigmas 3 or 6, feathery ; ovules one in each cell or the alternate cells 

 empty, anatropous. Fruit of 3-6 1 -seeded coriaceous carpels, separating 

 from a central axis and dehiscing in front. Seeds erect, terete, testa coria- 

 ceous. — Distrib. Temp, regions, many Australian ; species 12. — Etym. 

 rpeTs and yAaxiv, from the 3-pointed carpels. 



