Flora of central France. 60 



unformity in their vegetation. The Trifolium elegans is very 

 abundant in the lias ; but we find it generally where clay is 

 found combined in greater or less proportion with silex. 



The vegetation of Jurasic calcareous earth, divided into 

 inferior, middle, and superior oolite, is characterised by 

 the abundance of certain plants which are never found 

 in primitive lands, and that we find very rarely in more 

 modern formations : such are the Adonis aestivalis et flam- 

 mea, Erysimum odoratum et orientale, Thlaspsi montanum, 

 Hypericum montanum, Linum montanum, Corronilla minima 

 et varia, Hippocrepis comosa, Buplevrum protractum et fal- 

 catum, Ptychotis heterophylla, Sison amomum et segetum, 

 Peucedanum cervaria, Libanotis montana, Cornus mas, Sene- 

 cio eruccefolius, Inula salicina, Chrysanthemum corymbosum, 

 Phyteuma orbiculare, Campanula repunculoides, Gentiana 

 germanica et cruciata, Anchusa italica, Orobanche cruenta 

 Teucrium montanum, Globaria vulgaris, Asarum euaropceum, 

 Orchis odoratissima, Galeata pyramidalis, Ophrys apifera, 

 arachnitis, antropophora, myodes ; Epipactis rubra, Pha- 

 langium ramosum, Convallaria polygonatvim, Carex gyno- 

 basis, Melica ciliata, Sesleria ccerulea. 



The cretaceous lands consisting of the inferior, middle, and 

 superior chalk formation, sends forth a vegetation which varies 

 according to the nature of their upper surface. When car- 

 bonate of lime or clays predominate, we observe many plants 

 of lias and calcareous grounds, some Cruciferae, especially 

 Diplotaxis and Sisymbrium, which seem to delight in chalky 

 grounds. 



When sand or silicious gravel is found at the surface of 

 the soil, then the vegetation approximates that of the old 

 red sandstone, or even granite. The origin and constitu- 

 tion of the soil of tertiary lands being very different ac- 

 cording as those lands have been produced from isolated 

 deposits formed in circumscribed localities, or thrown on 

 sea shores, or formed at the bottom of vast fresh- water lakes, 



K 



