PREFACE. 



vii 



mittee of the Royal Horticultural Society. He has 

 also to thank Messrs. G. Massee, L. A. Boodle, F.L.S., 

 W. T. Saxton, F.L.S., E. S. Salmon, F.L.S., and 

 W. H. Hammond, for some beautiful photographs. 

 To Mr. Boodle he is also indebted for some important 

 suggestions and discussions bearing on various subjects 

 treated of in the work. 



Also to Mr. John Hopkinson, F.L.S., Secretary of 

 the Ray Society, for a great deal of assistance in 

 compiling the details of the bibliographical references. 



W. 0. WORSDELL. 



7th October, 1915. 



