70 MONOECIA— MONANDRIA. Zannichellia. 



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

 tumid and rugged at the outer edge ; tipped vi^ith the 

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

 monocotyledonous, with a very thin, simple, membra- 

 nous skin. Embryo central, tapering, incurved. Alhimen 

 none. 

 Slender, branched, floating Jierhs; submersed, except when 

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

 linear, entire. Fl. axillary, in pairs. 



1. Z. palustris. Common Horned-pondweed. 



Anther of four cells. Stigmas entire. 



Z. palustris. Lmn.Sp,Pm7o. Willd. v.4. \S\. 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 major, foliis gramineis acutis, fiore cum apice quadri- 



capsulari, embryonis clypeolis integris, et vasculo iion barbato, 



capsulis seminum adcostam dentatis. Mich. Gen. 71. t.34.f. 1. 

 Aponogeton aquaticum graminifoHum, staminibus singularibus. 



Ponted. Anthol. I 17. Rail Syn. 135. 

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



Prodr. 101. 

 Potamogeito similis^ graminifolia ramosa, et ad genicula polyce- 



ratos. Pluk. Almag. 305. Phyt. t.\02.f.7. 

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



In ponds and ditches. 



Annual. July. 



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

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

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

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

 cluding one barren flower, 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. 



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

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

 t. 34./. 2 3 and if he be correct as to the 2 cells of its anther, 

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

 probably be found in England. 



