INTRODUCTION 



tremities cylindrical sporangia filled with minute spores. The bituminous coal 

 in many instances is made up almost entirely of these spores and spore-cases. 



Another important group of trees which reached their maximum in the 

 Carboniferous Period were the Conifers, represented to-day by our Firs and 

 Pines. Those found in the coal-beds were closely related to the Araucarias, 

 and in many districts their fossil fruits have been found in great quantities. 



There were also at this time lofty trees or bushes with multipinnate 

 leaves several feet in length, in the shade of which other smaller species 

 grew and flourished. 



Through the eons life and death marched hand in hand, and the accumu- 

 lations of vegetable material, caused by the steady yearly shedding of leaves, 

 fronds, and spores, and the decay of fallen giants, continued to grow, being 

 subjected to an ever-increasing pressure, and gradually being covered by 

 sedimentary deposits, beneath which they might remain till the genius of 

 man should extract them from the depths of the earth to serve the wants of 

 industry and his own dwelling. 



LEAF STRUCTURE, FORM, AND FUNCTIONS 



We have referred to the more aesthetic beauty of trees as exemplified in 

 their general outline and ramification, but it is probably the foliage, with its 

 ever-varying form and colours, and its niceties of light and shade, which will 

 appeal most to the casual observer. 



We cannot here enter into a systematic description of the various forms 

 of leaves, but it is a matter of vital importance in the identification of 

 species, and, owing to the fact that the life of the flowers is at most a short 

 one, it is often our chief guide. 



Not only do leaves vary greatly in their arrangement on the stem and 



in their outline, but they exhibit many minute differences in colour and 



texture, each with its own appellation, and for the meaning of these the 



student must be referred to the Glossary. This infinite variety of leaf form 



and structure is intimately connected with the environment of the plant. 



The deep incisions and clefts which give such beauty to the outline of 



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