GL. i,] MPNANDB.IA. MONOGYNIA. 47 



* Opaque, and very brittle. 



1. C. vulgdris. Common Stoneioort, or Water Horse-tail. Steins 

 branched, obscurely striated, smooth, never entirely incrusted ; 

 whorled branches awl- shaped, fertile ones with numerous short 

 bracteas, three or four of which are much longer than the germen. 

 From six to ten or more inches in length : principal branches al- 

 ternate : germen egg-shaped, sessile, in the centre of the floral 

 leaves : anther sessile, upon the base of the germen. The whole 

 plant green when fresh, usually studded with whitish, calcareous 

 particles, and extremely fetid ; when dry, hard and brittle. An- 

 nual : flowers in July and August : grows in muddy ditches, pools, 

 and slow streams, entirely immersed : common. Eng. Bot. vol. v, 

 pi. 336. Eng. Fl. vol. i. p. 6. 5 . 



2. C.Hedwigii. Hedwig s Water Horse-tail Stems branched, elon- 

 gated, obscurely striated, smooth, sometimes partially incrusted ; 

 whorled branches awl-shaped, fertile ones with numerous short 

 bracteas, three or four of which are shorter than the accompanying 



-germen. Larger than the preceding, with more numerous fe'rtile 



branches. Annual : flowers in July and August : grows immersed 

 in still pools: rare*, Buxstead, Sussex; near Croft, Yorkshire. 

 Eng* Fl. vol. v. part i. p. 246. 6. 



3. C. dspera. Rough Water Horse-tail. Stems slender, obscurely 

 striated, everywhere covered with small spreading spines ; whorled 

 branches awl-shaped, the fertile ones with numerous short bracteas, 



those accompanying the germen of uncertain length. 'Annual : 



flowers in June and July: grows in pools in peat bogs: rare. 

 Orkney; Prestwick Carr, Northumberland, Durham. Eng. Fl. 

 vol. v. part i. p. 246. 7. 



4. C. hispida. Prickly Water Horse-tail. Stems furrowed, co- 

 vered by a calcareous crust, and armed above with small deflected 

 prickles ; whorled branches awl-shaped, fertile ones with numerous 



bracteas, of which three or four are longer than the germen. 



Larger than the three preceding species. Annual : flowers in July 

 and August: grows immersed in pools in turfy places : common. 

 Eng. Bot. vol. vii. pi. 463. Eng. FL vol. i. p. 7. A small variety of 

 this plant, without prickles, is sometimes met with. Eng. Fl. vol. i. 

 p. 7. The above four species of Char a may with propriety be re- 

 duced to one, C. vulgdris, of which the three others are probably 

 mere varieties. 8. 



* * Transparent and flexible. 



5. C. translucent. Great transparent Water Horse-tail, Stems elon- 

 gated, glossy ; branches of the whorls elongated, simple, cylindrical, 

 obtuse, those bearing flowers axillar, compound ; bracteas indistinct, 



or wanting. The largest, the brightest coloured, and most glossy 



of all the species here described. Annual : flowers in June and 

 July : grows in stagnant pools : rare in England and Ireland, more 

 common in Scotland. Eng. Bot. voL xxvi. pi. 1855. Eng. FL 

 vol. i. p. 8. 9. 



6. C.flexilis. Smooth Water Horse-tail. Stems repeatedly forked ; 

 whorled branches generally simple, obtuse, those bearing flowers 



axiilar, compound ; braeteas wanting, or very indistinct Stems 



from one to two feet long, slender, green, not crusted: anthers 

 sometimes solitary, but generally accompanied with two gennens, 

 or with one only, at the forks of the whorled branches. More 



