2 PHARMACEUTICAL BOTANY 



8. Phytopalaeontology or Geological Botany treats of plants of 

 former ages of the earth's history traceable in their fossil remains. 



9. Etiology is the study of the causes of various phenomena ex- 

 hibited by plants. 



10. Economic or Applied Botany deals with the science from a 

 practical standpoint, showing the special adaptation of the vegetable 

 kingdom to the needs of everyday life. It comprises a number of 

 subdivisions, viz.: Agricultural Botany, Horticulture, Forestry, 

 Plant Breeding, and Pharmaceutical Botany. Pharmaceutical 

 Botany considers plants or their parts with reference to their use 

 as drugs. It interlocks very closely with other departments of 

 botanical science. 



PRINCIPLES OF CLASSIFICATION 



The classification of plants is an attempt to express the exact 

 kinship which is believed to exist among them. By grouping to- 

 gether those plants which are in some respects similar and combining 

 these groups with others, it is possible to form something like an 

 orderly system of classification. Such a system based upon natural 

 resemblances is called a natural system. In a natural system of 

 classification every individual plant belongs to a species, every species 

 to a genus, every genus to a family, every family to an order, every 

 order to a class, every class to a division. In many instances species 

 may be subdivided into -varieties or races. The crossing of two 

 varieties or species, rarely of two genera, gives rise to a hybrid. 

 Thus, the species Papaver somniferum which yields the opium of the 

 Pharmacopoeia belongs to the genus Papaver, being placed in this 

 genus with other species which have one or more essential character- 

 istics in common. The genera Papaver, Sanguinaria and Cheli- 

 donium, while differing from each other in certain essential respects, 

 nevertheless agree in other particulars such as having latex, perfect 

 flowers, capsular fruits, etc., and so are placed in the Papaveraceae 

 family. The Papaveracea family and the Fumariacea family are 

 closely allied, the latter only differing from the former in having 

 irregular petals, usually diadelphous stamens and non-oily albumen 

 and so both of these families are placed in the order Papaverales. 

 The orders Papaverales, Geraniales, Sapindales, Rhamnales, etc., are 



