DETERMINATIOX OF FOSSIL PLANTS. 



Determination of Fossil Plants. 



Fossil plants are by no means so easily examined as recent 

 species. They are seldom found in a complete state. Frag- 

 ments of stems, leaves, and fruits, are the data by which the 

 plant is to be determined. It is very rare to find any traces 

 of the flowers. The parts of fossil 

 plants are usually separated from each 

 other, and it is difficult to ascertain 

 what are the portions which should be 

 associated together so as to complete an 

 individual plant. Specimens are some- 

 times preserved, so that the anatomical 

 structure of the organs, especially of 

 the stem, can be detected by very 

 thin slices placed under the micro- 

 scope. In the case of some stems the 

 presence of punctated woody tissue 

 (Fig. 1) lias proved of great service as 

 regards fossil Botany ; this structure, Fig. i. 



along with the absence of large pitted ducts, serving to 

 distinguish Conifers. The presence of scalariform vessels 

 indicates a plant belonging to the vascular Crj^ptogams, of 

 which the fern is the best known example. The cautions 

 to be observed in determining fossil plants are noticed by 

 Dr. Hooker in the JNIemoirs of the Geological Survey of 

 Great Britain (vol. ii. p. 387). At the present day, the 

 same fern may have different forms of fronds, which, un- 

 less they were found united, might be reckoned distinct 

 genera; and remarkable examples are seen in Niphobolus 

 rupestris and Lindsa3a cordata. Moreover, we find the same 

 form of frond belonging to several different genera, which can 



Fig. 1. Section of Peuce JVithajni, after Lindley and Hutton, a 

 fossil Conifer of the coal epoch. Punctated woody tissue seen. 



