458 PONDWEEDS. [March, 



* 

 Note. — The two following stragglers from cultivation are 

 entered as species uncertain in locality ; they may grow acci- 

 dentally in many places^ though rarely established in any : — 

 Armoracia rusticana, Camelina saliva. 



PONDWEEDS. 



History and Description of the British Species usually arranged 

 under the Natural Order Potamace^. 



The following monograph of the British aquatic plants usu- 

 ally arranged under the Natural Order Potamacea, and under the 

 genera Potamogeton, Ruppia, Zannichellia, and Zostera, is drawn 

 up in order to present the inquisitive reader with a comprehensive 

 and popular, or simple and intelligible, digest of our present know- 

 ledge of the history, characters, and distribution of the species 

 belonging to this Order, and their genera, viz. such as are of 

 British growth, which have been found, or are noAv found, in the 

 rivers, lakes, ponds, ditches, etc., of the fresh, or salt, or brackish 

 waters of the United Kingdom. 



The ancient history of the plants which constitute this Order 

 is almost, if not quite, as obscure as are several of the species 

 themselves. 



The most ancient and venerable botanical authority, viz. 

 Theophrastus, cannot, with safety, be quoted as having ob- 

 served and described any species of Potamogeton. He hints that 

 some marine A1g(S grew on the shores of Greece, and that in 

 the great ocean, beyond the pillars of Hercules, i. e. outside of 

 the Strait of Gibraltar, there were fuci so large that they could 

 not be grasped by the hand. This will not appear marvellous to 

 marine botanists who have seen the long and stout stems of 

 tangle, or sea-ware, which are frequently, in stormy seasons, 

 strewed on our shores."^ 



DioscoRiDEs, who lived at least about four hundred years 



* Sprengel quotes Theophrastus as the observer of Potamogeton serratus, Hud- 

 son, P. crispus of authors, a plant which the father of botany names rpi^oXos ev 

 TOis eAcoSeo-t tcov irorafxcuv, "the Trilulus which grows in marshes by rivers," or 

 " of rivers." Ahnost all the commentators on Theophrastus, certainly Scaliger and 

 Bodeeus (see their folio edition, 1644), call this plant Tribultis aquaticus, which 

 is a synonym of Trapa natans, Water Caltrops of the moderns, and well-known 

 to the ancients, but both generically and specifically distinct from the Pondweeds. 



