214 coLitf CLOUT'S CALENDAR. 



have several acclimatized varieties ; but they do not 

 spread like the regular weeds, nor have they the same 

 strength of constitution which enables the claytonia and 

 the Michaelmas daisy to compete successfully with the 

 old-established weeds of cultivation in southern Europe. 

 Even more interesting, however, than these aliens, 

 which owe their introduction directly .or indirectly to 

 man, are the real natural colonists from America, which 

 are found sparingly in many places along our exposed 

 western coasts, from the Hebrides to Cornwall. Many 

 of them, no doubt, have been acclimatized in Britain 

 long before the discovery of America by the Spaniards ; 

 for all the evidence goes to suggest that their seeds must 

 have been carried across the Atlantic by the agency of 

 sea-birds, or must have been wafted over in the crevices 

 of drift-wood, or must have been washed ashore by the 

 favoring current of the Gulf Stream. For example, in 

 the lakes and tarns of the Isle of Skye, Coll, and the 

 outer Hebrides, as well as in the shallow loughs of Con- 

 nemara and Kerry, a slender graceful water-plant with 

 pellucid leaves grows abundantly over the soft mud, and 

 forms a tufted waving carpet above the smooth shining 

 bottom, with its white jointed fibres and grass-like 

 blades. This pretty weed belongs to a family otherwise 

 wholly unrepresented in Europe, but common in all the 

 still waters of America. Clearly, from the nature of its 

 distribution here only along the extreme western belt 

 of the British Isles, where the coast lies fully exposed to 

 the long wash of the Atlantic it must have reached our 

 shores by some such casual accident as those which have 

 peopled oceanic islands, like the Azores, with their scanty 

 fauna and flora. Its seeds must have clung to the legs of 

 wading birds blown eastward before a northern cyclone, 

 or else its roots must have been torn up entire and cast 



