THE CROWFOOT TRIBE. 13 



represented them to be ; for in the middle of every 

 little vein is a sort of windpipe which conveys vital 

 air to their extremest points. 



Such is the way in w^hich the veins of the leaf are 

 disposed in the Crowfoot. It is very essential that 

 you should pay attention to this netted branching 

 arrangement, because one of the great natural divi- 

 sions of the vegetable kingdom is to be known by that 

 circumstance. One of the great natural divisions 

 of plants is called Exogenous, because the stems 

 grow by addition to the outside of their w^oody centre ; 

 the same division is also called Dicotyledonous, 

 because the embryo has two seed-leaves or cotyledons. 

 You may generally recognize such plants by their 

 leaves having netted veins ; so that you see it is neither 

 necessary to w^atch the stem to see how it grows, nor 

 to examine the seed under a microscope in order to 

 count the cotyledons, if you w ould ascertain whether 

 a plant is Exogenous or not ; the manifest arrange- 

 ment of the veins in the leaf reveals the secret struc- 

 ture of the stem. 



If you have rightly understood what I have ex- 

 plained thus far, you will not only have mastered 

 several terms, but you will actually have made one 

 important step in the study you have taken up : you 

 will have become acquainted with the essential charac- 

 ters of a large and important natural order of plants, 

 called the Crowfoot tribe (or Ranunculacese), 

 amonfT which are some that are remarkable for the 

 virulent poison which often lurks beneath their beau- 

 tiful exterior. The Crowfoot genus itself contains 



