CH. Xl] CLASSIFICATION. 141 



cotyledons, and for that reason known as Dicotyledons; 

 the tulip, on the other hand, which formed the subject 

 of an earlier chapter, belongs to the Monocotyledons) or 

 plants with a single cotyledon. 



The Seed-plants are classified into a number of 

 divisions known as Natural Orders, and the arrangement 

 of flowering plants into these groups is an important part 

 of the systematic botanist's work. The student of Ele- 

 mentary Biology is not expected to know this part of the 

 subject, but he ought to have a rough idea of the general 

 plan on which plants and animals are grouped. In collect- 

 ing material for the study of the flower, the student 

 will come across two kinds of buttercup, not identical in 

 appearance, but both obviously buttercups. This relation- 

 ship is technically expressed by saying that both plants 

 belong to the genus Ranunculus, but that they are of 

 different species : for instance Ranunculus acris and Ra- 

 nunculus bulbosus. Besides the genus Ranunculus there 

 are other plants whose flowers are plainly built on the 

 same general plan, for instance the Marsh Marigold (Caltha 

 palustris) and the Globe Flower (Trollius Europceus). 

 Other flowers such as the Columbine (Aquilegia) and 

 the Larkspur (Delphinium) do not obviously resemble 

 buttercups, but are found by analysis to be of the same 

 structural type. All these genera, Ranunculus, Caltha, 

 Trollius, Aquilegia, Delphinium and many others are 

 massed together into the Natural Order Ranunculacece, 

 so named after one of its constituent genera, Ranunculus. 

 In the same way the bean (Vicia faba), the pea (Pisum), 

 the lupin (Lupinus), the clover (Trifolium) and scores of 



