1893. the Flora of the Pollard Willotus near Cambridge. 85 



W. and B. Loew. 



Animal distributed (I., II.) 27-5 23-33 



Wind „ (III, IV., V.) 53-75 5333 



Doubtful (VI.) 18-75 23-33 



But while in number of species wind-distribution holds the 

 first place, in number of plants animal-distributed species form 

 61 per cent, of the total. 



The figures show very well the efi'ect of possessing a good 

 distribution mechanism. Only those plants which possess such 

 occur in any important number in the willow tops. Even such 

 common plants as Brassica, Capsella, TrifoUum, Bellis and others, 

 do not appear in the list. 



Another important conclusion on distribution that can be drawn 

 from these observations, is that a- seed is rarely carried by its dis- 

 tribution mechanism to a distance of more than a few hundred 

 yards. 



Plants were never found in willows more than 200 yards from 

 others of the same species upon the ground, except in one instance, 

 a plant of Rihes Grossidaria in section H, which was more than 

 half a mile from any other, but as it was some years old, probably 

 there may formerly have been a gooseberry plant near at hand. 



It is impossible to give the details of every tree examined, 

 within the limits of a short paper, but in making the observations 

 this fact of short-distance carriage was forced upon our notice at 

 every step. A consideration of the Table will to some extent show 

 this. Several plants require also special notes and these may 

 conveniently be here introduced. 



Rhamnus. Chiefly found wild in the southern part of the 

 district, where the records occur. 



Acer, Fraxinus, Syringa, Ulmus. These only occur in the 

 wooded districts, and always close to trees. 



Rosa. Common in all districts except the open fen (H). Even 

 here there were often plenty of roses within half a mile, yet none 

 were found in the willow tops. 



Rihes. Common near gardens, but never found far from them, 

 hence its decrease in sections F, G, H. 



Epilohium. Though its seeds are so light, and it is so common, 

 yet it only occurs in any number in section B, opposite the wood 

 in which it forms a large part of the undergrowth. 



Anthriscus. Occurs in most districts, being very common upon 

 the soil. It forms the chief portion of Class VI. as regards actual 

 numbers. 



Hedera. It is probable that many of the records of the occur- 

 rence of ivy are due to its having climbed up the tree, taken root 

 in the top and then died away below. Several cases were found 

 where this proces? was going on, the stems dying away and leaving 



