INTRODUCTION XXXV 



a map. Botanists should unceasingly endeavour to arrive at a 

 natural system of classification. Such a natural system is the 

 final aim of botanical science. Our insufficient knowledge of 

 plants is what renders such a system impracticable at present." 



Botanists nowadays seldom employ the Linnsean System, pre- 

 ferring the more difficult but more instructive Natural System. 

 In this we may reverently be said to be thinking out for ourselves 

 the thoughts of the Creator, for, according to the theory of 

 descent, which gives us the most rational explanation of the 

 meaning of resemblances, we are reconstructing the pedigree 

 of the Vegetable Kingdom. 



One of the most striking assurances that our system is truly 

 natural is afforded us by the discovery that many groups of genera 

 classed together in what we term natural orders, solely on account 

 of structural characters, agree closely also in their properties. 

 This obviously also gives a practical utility to the system. In the 

 present work, for instance, adopting a system based upon those of 

 Antoine Laurent de Jussieu (1774) and Auguste Pyrame de 

 Candolle (18 13), we group the genera into natural orders, the 

 Latin names of which are adjectival, ending in a, agreeing with 

 the word plantce understood. The name of the first of these 

 orders, Ranunculacea, means " plants allied to Ranunculus," and 

 the Order includes, in addition to the Buttercups (Ranunculus), 

 Anemones, Hellebores, Aconites, Larkspurs, Columbines, 

 Pseonies, Clematis, and others. These agree in the absence of 

 any union between the parts of their flowers and in having 

 hypogynous and generally numerous stamens ; but they also agree 

 in having an acrid, often poisonous, juice. Another large 

 Natural Order, the Crucifera, consists almost exclusively of 

 herbaceous plants with simple leaves, flowers without bracts, four 

 sepals, four petals, six stamens, of which four are longer than the 

 other two, and two united carpels forming a siliqua j but they 

 also agree in being wholesome and generally pungent from the 

 presence of oil of mustard. Yet another group, the Labiata, 

 agree in their square stems, opposite and decussate, simple 

 leaves, two-lipped (bi-labiate) corollas, four stamens, two long and 

 two short, and two carpels dividing into four nutlets ; but they 

 also agree in being aromatic from the presence of volatile essen- 

 tial oils in which are dissolved camphor-like substances. The 

 structure of a newly-discovered plant may thus afford a traveller 

 considerable information as to its probable properties. 



The Vegetable Kingdom is now generally divided into four sub- 

 kingdoms : the Thallophyta, including seaweeds and fungi ; the 

 Bryophyta, or mosses and liverworts ; the Pteridophyta, or ferns, 



