iv.l DICOTYLEDONS. 39 



simple fact that the first leaves of the plant are opposite) 

 is common to plants with irregularly net-veined leaves, 

 and with the parts of their flowers in fours or fives with 

 but a comparatively small number of exceptions, botanists 

 employ the term DICOTYLEDONS as the name of a great 

 Class of flowering plants, including all those which 

 present the above characters. 



19. It must always be borne in mind, however, that 

 none of these characters are absolute. They are always 

 subject to exception. So that plants which exhibit a 

 departure from the prevalent type of Dicotyledons in any 

 single character only are still referred to the same class. 

 Thus we have a few Dicotyledons which are actually 

 destitute of cotyledons, or which have but one, or more 

 than two ; we have some with parallel-veined leaves, and 

 others with the parts of the flower in threes. But in all 

 these cases the question as to which Class the plant shall 

 be referred, is decided, not by any solitary character, but 

 by the sum or preponderance of characters which it 

 presents. 



The structure of the stem, and mode of growth of the 

 wood, we shall speak of in a later chapter. 



