Ku PP ia.'\ FLUVIALES. 267 



Rivers, ditches, and bog-drain?. Ditches near Limerick, not com- 

 mon ; Mr. W. H. Harvey. Enagh Lough, and in the river Roe, 

 County of Derry ; Mr. D. Moore. FL July. %. As Mr. Wilson 

 states in his letter to Doctor Hooker, " This does in some situations 

 much resemble P. lucens." It is remarkable for its reddish olive- 

 colour, and is perhaps better known by its general aspect than by any 

 character that can be applied to it. 



12. P. natans, Linn. Sharp-fruited broad-leav:d Pond-weed. 

 Lower leaves submembranaceous or wanting, upper elliptical, 

 coriaceous, floating; all on long stalks, many-nerved, distinctly 

 cellular; fruit carinated. Br. FL 1. p. 76. ' E. Eot. t. 18:22. 

 E. Fl. v. i. p. 228. 



Stagnant waters and slow streams, frequent. FL June, July. It . 

 Stem branching, several feet long, submersed ; spike raised one or two 

 inches above the water ; flowers sessile, olive-green, with yellow an- 

 thers. A very troublesome weed in ponds, when the bottom consists 

 of a clay soil. 



2. ZOSTERA. Linn. Grass-wrack. 



Stamens and pistils inserted in two rows upon one side of a 

 spadix. Spatha foliaceous. Anthers ovate, sessile, alter- 

 nating with the gerraens. Germ-en ovate. Style bifid. 

 Drupe with one seed. Name ; ^0-7^/3, a girdle, or ribbon, 

 which the leaves somewhat resemble. 



Moncecia. Monandria. 



1. Z. marina, Linn. Common Grass-iurach. Leaves entire, 

 somewhat 3-nerved ; stem roundish. Br. FL I. p. 385. E. hi. 

 v. i. p. 5. E. Eot. t. 467. 



Creeks and ditches of salt water and on the sea-shores, common. FL 

 through the summer. 7. Stems various in length, as are the linear, 

 obtuse, somewhat 3-nerved leaves, which have sheathing bases. Spa- 

 dix linear, arising from a sheathing portion of the leaf, which thus 

 forms the spatha. Flowers green, on one side of the spadix, quite 

 destitute of perianth, in two rows. Pistils and anthers alternate. This 

 is the now well known "Aha ( Ulva,) marina," used for beds, &c. 



3. RUFPIA. Linn. Ruppia. 



Flowers two, on a spadix arising from the sheathing bases of 

 the leaves, which perform the office of a spatha. Perianth 

 none. Drupes four, pedicellate, their nuts one-seeded. 

 Named after Henry Bernard Ruppius, author of Flora 

 Jenensis, in 1718. Tetrandria. Tetragynia. 



1. R. maritlma, Linn. Sea Ruppia. JBr. FL \.p.ll. E. 

 FL v. i. p. 237. E. Bot. t. 136. 



Salt-water pools and ditches. Near the North Wall, Dublin ; Dr. 

 R. Scott. Near Passage, County of Cork ; Dr. D. 7/. Scott. Abun- 

 dant along the shore of Lough Foyle ; Mr. D. Moore. FL July, 

 Aug. If . " Stems slender, filiform, flexuose, branched, leafy. Leave* 



