ANT PLANTS 3" 



theless, ant-inhabited trees are common. In America the 

 imbauba tree is regularly inhabited in regions subjected to 

 flooding, an obvious advantage to the warrior ant, though 

 in such regions the ' leaf-cutters with their subterranean 

 nests are absent. Species of Cecropia are known which do 

 not harbour ants and which are not attacked. The ravages 

 of the leaf-cutters are said to have been exaggerated ; in 

 fact, the ants are most destructive to cultivated plants, 

 damage to which is most likely to be noticed — and resented. 

 Ridley (1910) supports the protection theory, and points 

 out that plant enemies other than leaf-cutters may 

 be attacked by the warrior ants. On the other hand, 

 Ihering states that the ant Azteca Miilleri is so completely 

 dependent on Cecropia adenopus that it cannot survive 

 without its host tree, while the imbauba can grow perfectly 

 well without the ant. 



We may sum up by saying that recent opinion tends to 

 emphasise the ability of the ant to make use of any oppor- 

 tunities, and to cast doubt on the reciprocal advantage gained 

 by the plant. There may, however, be a danger in denying 

 all use to the plant in the possible protection afforded against 

 various animal enemies. We may here note that the extra- 

 floral nectaries found on some European plants, as on the 

 backs of the leaves of the cherry laurel, and on the stipules 

 of the bush vetch, have been supposed to attract ants which 

 in their turn protect the flowers from insect damage. There 

 is little evidence that the plant really benefits. 



Among the many functions which have been assigned to 

 the violent folding of the leaflets of Mimosa pudica when the 

 plant is shaken, is the scaring away of grazing animals. 

 Jost quotes a letter of Heinricher descriptive of the behaviour 

 of the sensitive plant in the botanic garden in Penang : 

 " It was there I first met Mimosa pudica as a thick growing, 

 vigorous weed, a third of a metre high and more. If one 

 walked into the low thicket there appeared, as a result of 

 the very prompt reaction, an empty, burnt-out looking 

 space enlarging with every forward step. The same result 

 must follow the entrance of a cow or other similar animal . . . 



