52 



FIELD AND WOODLAND PLANTS 



know so well, are conspicuous, and are visited and pollinated by 

 insects, but they produce few or no seeds. In the autumn another 

 kind of flower is formed, inconspicuous ones that often possess no 

 petals, and which do not open. These are fertilised by their own 

 pollen, and produce abundance of seed. 



Soon after the appearance of the Dog Violet — usually early 



THE DOG VIOLET. 



in May — we meet with the flowers of the Wood Sorrel or Alleluia 

 {Oxalis Acetosella), a plant which is often included with the Crane's- 

 bills in the order Geraniacece, but sometimes placed in a separate 

 small order {Oxalidacece) containing only three British species. It 

 is a very pretty little plant, of an acid nature, springing from a 

 creeping rhizome. The leaves are radical, ternate, hairy, and 

 sensitive, folding vertically at night in such a manner that the 

 lower surfaces, containing the stomata, are completely covered, 

 and thus loss by evaporation prevented. The flowers are usually 



