95. NAIADACE^. 355 



2. RuppiA Linn. Tassel-Pondweed. 



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

 oblong 14 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. pahstris (L.) ; style at least half as long as the fruit. — 

 E.B. 1844. B. 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.) j 

 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. |3. Brackish water. A. or P. V.— VIII. 



Order XCV. NAIADACE^. 



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

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

 2 — 4, fihform. 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. 

 Ban-en fl. of 1 stamen. Fertile : style short ; stigmas 2—4, 

 filiform. 



1. ZosTERA Zmre. Grass-wrack. 



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

 short with clasping bands, nuts smooth. — E. B.S. 2931. R.xii. 2. 

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

 long as the inflated oblong-lanceolate spaths. — Muddy estuaries 

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



