

.CL, IV.] TETRANDKIA TETKAGYNIA. 107 



flowered. Nearly as large as the preceding, the largest British 



species. Perennial : flowers in July : grows in pools and lakes in 

 Scotland : rare. Berwickshire ; Moss of Litie, Nairnshire ; Loch- 

 leven. Brit. Fl. 4th ed. p. 70. 270. 



8. P. lanceoldtus. Lance-shaped Pond-weed. Leaves lance- 

 shaped, membranous, tapering at the base, sessile ; spikes dense, 



few-flowered. Leaves marked with ehain-like reticulations near 



the ribs : spike small, short. Perennial : flowers in July and Au- 

 gust : grows in pools and slow streams : rare. Eng. Bot. vol. xxviii. 

 pi. 1985. Eng. FL vol. i. p. 233. 271. 



9. P. crispus. Curled Pond-weed. Leaves lance-shaped, three- 

 nerved, waved, serrate, alternate, the upper opposite. Leaves 



sessile, bright green : flowers yellowish-green, in short, loose spikes. 

 Perennial : flowers in June and July : grows in ditches, pools, and 

 rivulets: common. Eng. Bot. vol.xv.pl. 1012. Eng. Fl. vol. i. p. 233. 



272. 



10. P. gramin'eus. Grassy Pond-weed. Leaves linear, tapering 

 towards the base, alternate, sessile ; stem round, forked ; flower- 

 stalks little longer than the spikes. Leaves bright-green, grassy- 

 looking : spikes egg-shaped, dense. Perennial : flowers in July : 

 grows in ditches and streams : rare. Eng. Bot. vol. xxxii. pi. 2253. 

 Eng. Fl. vol. i. p, 235. 273. 



11. P. pusil'lus. Small Pond-weed. Leaves linear, three-ribbed, 

 opposite and alternate, spreading at the base ; stem round ; flower- 

 stalks many times longer than the spikes. Leaves very narrow, 



pointed, much expanded at the base : spikes nearly globular. Pe- 

 rennial: flowers in July: grows in ponds, ditches, and slow streams: 

 not uncommon. Eng. Bot. vol. iii. pi. 215. Eng. Fl. vol. i. p. 236. 

 A variety with broader leaves and interrupted spike is the P. com- 

 pressus* Flat-stalked Pond-weed. Eng. Bot. vol. vi. pi. 418. Eng. 

 Fl. vol. i. p. 234. 274. 



12. P. pectindtus. Fennel-leaved Pond-weed. Leaves bristle- 

 shaped, one-ribbed, parallel, closely set in two rows ; spikes inter- 

 rupted. Leaves alternate, bright-green : spikes few, with inter- 

 ruptions. Perennial : flowers in July : grows in ditches, pools, and 

 rivers : rare. Eng. Bot. vol. v. pi. 323. Eng. Fl. vol. i. p. 237. 275. 



13. P.acutifolius. Sharp-leaved Pond-tveed. Leaves linear, taper- 

 pointed, with three principal and numerous close parallel interme- 

 diate nerves, occupying the whole surface : spikes oval, compact, 

 about equal in length with the short panicle. Perennial: flowers 

 in July. Found by Mr. Borrer, in marsh-ditches at Amberley, 

 Henfield, and Lewes, Sussex. Eng. Bot. Suppl. pi. 2609. Brit. Fl. 

 4th ed. p. 69. 276. 



14. P. zoster csfolius. Grass-wrack-like Pond-weed. Leaves 

 broadly linear, acute, with three principal and numerous close pa- 

 rallel intermediate nerves, occupying the whole surface : spikes 

 cylindrical, upon long peduncles. Perennial: flowers in July: 

 grows in ditches : rare. Rivulet at Hovingham, Yorkshire : Lakes 

 of Rescobie and Forfar. Eng. Bot. Suppl. pi. 2685. P. cuspidatus. 

 Eng. Fl. vol. i. p. 234. 277. 



18. RU'PPIA. TASSEL- GRASS. 



Calyx none. Corolla none. Anthers four, sessile, equal, 

 roundish. Germens four, egg-shaped, close together. Styles 



