PAL^EOBOTANY. 



CHAPTER XLIIL 



GENERAL RELATIONS OF PLANTS TO TIME. 



THE subject of Palagobotany or Palaeophytology is one which 

 is far too vast to be treated of in a work of this nature ; whilst 

 it is one which is of less importance to the general student than 

 that of Palaeozoology. For this reason, nothing further will be 

 attempted here than to give the briefest and most elementary 

 outline of the general distribution of plants in past time, to 

 which will be added a short summary of the chief forms of 

 vegetable life which characterise each of the great formations. 

 The following table shows the leading groups into which the 

 Vegetable Kingdom is divided : 



DIVISIONS OF THE VEGETABLE KINGDOM. 



I. CRYPTOGAMIC PLANTS (Gr. kruptos, concealed ; gamos, marriage), 

 distinguished by having no distinct flowers or fruit. They include 



a. Thallogens. Ex. Sea- weeds (Algce), Lichens, Mushrooms. 



b. Anogens. Ex, Liverworts, Mosses. 



c. Acrogens. Ex. Club-mosses (Lycopodiaiecs) ) '&ras, Horse-tails (Equi- 

 setacecs), 



II. PHANEROGAMIC PLANTS (Gr. pkaneros, conspicuous ; gamos, mar- 

 riage), distinguished by having distinct flowers and seeds. They are 

 divided into 



a. Endogens. Ex. Grasses, Palms, Lilies. These have endogenous stems, 

 showing no rings of growth, and the young plant possesses but a single 

 seed-lobe or " cotyledon." Hence they are often called Monocotyledons. 



b. Exogens. Ex. Pines and Cycads, with most ordinary shrubs, trees, 

 and flowering plants. The Pines and Cycads, with the fossil Sigillari<z, 

 have the seed naked, and are hence called Gymnosperms (Gr. gumnos, naked ; 

 sperma, seed). Ordinary trees and shrubs, on the other hand, have the 

 seed covered, and are therefore called Angiosperms. Both the Gymno- 

 sperms and Angiosperms have an exogenous mode of growth, with a true 

 bark and annual rings of growth. The seed also possesses two seed-lobes or 

 " cotyledons ; " and they are therefore often spoken of as Dicotyledons. 



