vi PREFACE 



Some words of explanation may be required in reference 

 to the definitions of flowers and fruits. In more advanced 

 works we are told that a flower is a collection of sporophylls 

 inserted on a simple axis. This definition seems to me im- 

 perfect. That the young carpels and stamens are homologous 

 with leaves, and particularly with sporophylls, is proved 

 beyond a doubt. But the mature carpel with the ripe ovules 

 is no longer homologous with a sporophyll ; it is a sporophyll 

 containing parasitic and symbiotic gametophytes. The sym- 

 biosis of the gametophytes and the sporophylls before, during, 

 and subsequent to fertilisation constitutes a phenomenon which 

 is unique in the vegetable kingdom. Consequently, it appears 

 that, when judged by the facts of the case and on historical 

 grounds, it is at least incomplete and inexpedient to employ 

 to the cone of Equisetum the same term as to the flower of a 

 Buttercup. A single flower of a Buttercup is no more a mere 

 collection of sporophylls than a frog is a fish because it passes 

 through the tadpole stage. In reference to the definition of 

 a fruit, I have followed that given in the "Lehrbuch der 

 Botariik" written by Professors Strasburger, Noll, Schenck, 

 and Schimper. The definition of a fruit is thus brought closer 

 to the popular usage of the term, while we are extricated from 

 any dilemma in reference to distinguishing between an inferior 

 and a false fruit. .. 



In conclusion, it should be stated that for the most part the 

 illustrations have, after careful consideration, been specially 

 executed by my friend Mr A. H. Church of Jesus College, 

 Oxford, to whose skill and care I am much indebted. To him, 

 also, I owe a careful revision of the proofs of this book. 

 Further assistance in the matter of illustrations has been 

 rendered by Mr A. Robinson of the University Museum, 

 Oxford. Students who desire a simple introduction to the 

 study of Microscopical Botany are recommended to procure 

 Dr D. H. Scott's "Structural Botany"; while those who 

 wish for a comprehensive work, dealing with the science as 

 a whole, will find all they require in " The Student's Text-book 

 of Botany," by Professor S. H. Vines. Finally, such students as 

 desire to identify wild British plants, and to do field-work, 

 will find Hayward's "Botanist's Pocket Book" an excellent 

 little work which contains all the necessary information. 



