95. NAIADACEJS. 355 



2. RUPPIA Linn. Tassel-Pondweed. 



1. R. maritima (L.) ; ped. long spirally twisted, anth. -cells 

 oblong 1^ times as long as broad, nut ovoid rather obliquely 

 erect. R. vii. 17. Whole plant stronger than the next. L. 

 very narrowly linear, formed as in Pot. pectinatus. Sheaths 

 large, inflated. Salt marshes in the south. P. VII. VIII. E. 



2. R. rostellata (Koch); ped. short not spiral, anth.-cells 

 squarish as long as broad, nut gibbous at base obliquely ascend- 

 ing when young. E. B. 136? R. vii. 17. Whole plant very 

 slender. L. rather filiform than linear. Sheaths small, close. 

 Salt marshes. P. VII. VIII. 



3. ZANNICHELLIA Linn. Horned Pondweed. 



1. Z. palustris (L.) ; style at least half as long as the fruit. 

 E. B. 1844. E. vii. 16. Floating. L. slender, opposite, filiform. 

 Fl. axillary, sessile. Anth. 2 4-celled. Style i as long as fruit. 

 Stigma generally notched at the margin. /3. Z. pedicellata (Fr.) ; 

 style as long as the fruit. Clusters usually stalked. Pedicels 

 elongated. \_Z. polycarpa (Nolte), style scarcely a sixth of the 

 length of the nut, has not been found in Britain.] Stagnant 

 water. . Brackish water. A. or P. V. VIII. 



Order XCV. NAIAD ACE^E. 



Fl. monoecious or dioecious, in a spath. Perianth 0. Stam. 

 free, 1 3. Ovary 1, superior, with 1 ovule. Style 1 ; stigmas 

 24, filiform. Fr. a nut inclosed in the persistent spath, 

 1 -celled, 1 -seeded, not bursting. Albumen 0. Embryo with a 

 thin skin having a lateral cleft. 



1. ZOSTERA. Fl. imperfect. Stam. and pistils inserted in 

 two rows upon one side of a spadix. Spath linear, leaflike. 

 Fl. naked. Anth. 1. Ovary 1 ; style 1 ; stigmas 2. 



2. NAIAS. Fl. imperfect, solitary, sheathed, no perianth. 

 Barren fl. of 1 stamen. Fertile : style short ; stigmas 2 4, 

 filiform. 



1. ZOSTERA Linn. Grass-wrack. 



1. Z. nflwa(Roth); 1. linear 1 -veined, ped. filiform, spadix 

 short with clasping bands, nuts smooth. E. B. S. 2.931. R. vii. 2. 

 Plant small, scarcely 3 in. long. L. slender. Ped. quite as 

 long as the inflated oblong-lanceolate spaths. Muddy estuarier 

 of the coast of England. P. ? VII. VIII. E. 



