214 RrPPIA. [class IV. OED£R m. 



Mountain nil, 

 Wand'ring its wiM course from the mountain's breast, 

 Now, with a biink fantastic, heather-drest, 

 And playing with the stooping flowers at will. 



It is therefore evident that few gardens possess such facilities for the 

 cultivation of aquatics, as to afford an opportunity of placing the vari- 

 ous kinds in situations at all approximating to that in which they are 

 found in nature. The truth of these remarks is borne out hy the fact, 

 that although numerous and extensive collections of terrestial plants 

 are to be found iu many parts of Great Britain, yet nowhere are aqua- 

 tic plants cultivated to the same extent, and with equal success. In 

 the genus in question, we have a striking illustration of this truth ; for, 

 although all the species possess foliage of peculiar beauty, yet when 

 removed from their natural habitations, some of them defy the skill of 

 the cultivator to preserve them alive for any length of time. Whilst, 

 however, a few of the genus are impatient of cultivation, others are of 

 remarkably robust growth ; and it is stated by Haller, that in the lakes 

 of Switzerland, the stems of P. serraturn extend to twenty fathoms in 

 length, and form, as it were, immense woods in the midst of these vast 

 reservoirs. The leaves and seeds of P. crispuin afford an agreeable 

 food for ducks, and the roots of P. natans are eaten by swans and other 

 large aquatic birds; whilst the leaves of all afford shelter, shade, and 

 spawning places for fish, as well as harbour for insects, from which 

 both birds and fish derive a great portion of their food. 



GENUS XX. RUP'PIA. Linn. Ruppia. 



Nat. Ord. Fluvia'les. 



Gen. Char. Floicers two, from the base of the leaves. Calyx and 

 corolla none. Seeds four, convex on one side, slightly keeled on 

 the other, and elevated on a short peduncle. Named in honour 

 of H. Bernard Ruppius, a botanical author. 



Ruppia differs from Potamogeton in being entirely destitute of 

 calyx, and also in having stalked seeds. 



1. R. marit'ima,'Lmvi. (Fig. 281.) Sea Ruppia. 



English Botany, t. 136.— English Flora, vol. i. p. 2.38.— Lindley, 

 Synopsis, p. 251.— Hooker, British Flora, vol. i. p. 79. 



Roots fibrous, growing in tufts from the lower joints of the slender, 

 flexuose, branched, leafy stern. Leaves alternate, linear, narrow, chan- 

 nelled, more or less acute, and clasping the stem at the base, forming a 

 sheath more or less dilated. Spikes about two-flowered, one below the 

 other, on short, solitary, axillary stalks. Anthers sessile, large, one- 

 celled, and bursting hoiizontally; during the time of flowering, the 



