PLANTS 



449 



Tceniopteris , Caulopteris, Clathropteris (PL VIII, Fig. 5) are 

 among the most important genera. In Virginia a magnificent 

 fern with very broad leaves, Maci'otceniopferis, is the most abun- 

 dant and characteristic of the Triassic plants there found. 



The Lycopods have undergone a great reduction since the Car- 

 boniferous, though a few straggling specimens of Sigillaria have 

 been found in the lower 

 Trias. On the other 

 hand, true Horsetails 

 of the modern genus 

 Equisetum now make 

 their first appearance, 

 and much surpass their 

 modern representatives 

 in size, having stems of 

 4 inches in thickness. 

 Rhizomes and stems of 

 these plants' are very 

 common, and dense 

 growths of them, like 

 cane-brakes, surround- 

 ed the inland seas and 

 salt lakes of the period. 



Cycads with their 

 stiff leaves abounded, 

 growing, doubtless, on 

 the dryer lowlands 

 above the swamps, most 

 of them belonging to 

 such genera as Plerophyllum, Zamites, and Otozamites (VIII, 6). 

 This group of plants is a characteristic Mesozoic one, and the era is 

 sometimes called the "Age of Cycads." On the hills and uplands 

 grew dense forests of Conifers, in appearance like the Araucarians, 

 which are found to-day in South America, Polynesia, and Australia. 

 Baiera, Araucarites, and the cypress-like Voltzia (Fig. 148), the 

 latter much resembling the Permian Walchia, are common genera. 



Voltzia heterophylla. (Fraas.) 



