70 MONOECIA— MONANDRIA. Zannichellia. 



what compressed, of 1 cell and 1 valve, not bursting ; 

 tumid and rugged at the outer edge ; tipped with the 

 permanent style. Seed solitary, of the form of the cell, 

 monocotyledonous, with a very thin, simple, membra- 

 nous s]ci7i. Embryo central, tapering, incurved. Albumen 

 none. 

 Slender, branched, floating herbs-, submersed, except when 

 in flower. Leaves simple, alternate, or partly opposite, 

 linear, entire. Tl. axillary, in pairs. 



1. Z, palustris. Common Horned-pondweed. 



Anther of four cells: Stigmas entire. 



Z. palustris. Linn. Sp. PL 1375. fVilld. v. 4. 181. Fl. Br. 955. 



Engl. Bot. V. 26. t. 1844, Hook. Scot. 258. Mill. Illustr. t. 77. 



Fl. Dan. t. 67. 

 Z. n. 1604. Hall. Hist. v. 2. 279. 

 Z. palustris majoVj foliis grainineis acutis, flore cum apice quadri- 



capsularij embryonis clypeolis integris, et vasculo non barbato, 



capsulis seminum ad costam dentatis. Mich. Gen. 71. t.34.f. 1. 

 Aponogeton aquaticum graminifolium, staminibus singularibus. 



Ponted.Anthol.\\7. RaiiSyn. 135. 

 Potamogeton capillaceum,capitulis ad alas trifidis. Bauh. Pin. 193. 



Prodr. 101. 

 Potamogeito similis, grarainifolia ramosa, et ad genicula polyce- 



ratos. Pluk. Almag. 305. Phyt. t. 102./. 7. 

 Horned Pondweed. Petiv. H. Brit. t. 6.f. 2. 



In ponds and ditches. 



Annual, July. 



Boot of several very slender fibres. Herb smooth. Stem thread- 

 shapedj much branched, leafy, 12 or 18 inches long, floating. 

 Leaves very narrow, acute, generally opposite under the Jlowers. 

 Bractea axillary, solitary, tubular, membranous, oblique j in- 

 cluding one barren Jlower, consisting of a simple stamen ; and 

 a fertile one on a short stalk. Anth. oblong, with 4 furrows and 

 as many cells. Germens 4 or 5, their stigmas ovate, spreading, 

 quite entire at the edges. Caps, tubercular, or rugged, at the 

 outer edge. 



rr 



Z. dentata of Willdenow, separated by him at my suggestion from 

 our British plant, was long ago well distinguished by Micheli, 

 t. 34./. 2 ; and if he be correct as to the 2 cells of its anther, 

 and the toothed stigmas, nothing can be more distinct. It may 

 probably be found in England. 



