FLORA 



NORTR AMERICA 



I. CORMOPHYTA. Endlicher. 



Dicotyledones, Monocotyledones, and Acotyledones in partj Juss. 



Plants consisting of a root and stem growing in op- 

 posite directions, composed of regular cellular tissue 

 traversed (except in the very lowest forms) by woody 

 fibre and vessels. Stem increasing in size either at the 

 apex and circumference simultaneously, or at the apex 

 solely, producing huds^ and (with few^ exceptions) dis- 

 tinct leaves at definite points and in regular order : the 

 cuticle usually furnished with stomata. Propagation 

 effected by means oi Jioiocrs and seeds in the higher 

 forms, and of spoi'es in the lower. 



Class I. EXOGENOUS OR DICOTYLEDONOUS 

 PLANTS. 



Flowering plants.— Stem with a distinct bark and pith, sepa- 

 rated from each other by an interposed zone consisting of woody 

 fibre, ducts, and spiral vessels : increase in diameter effected by 

 the successive deposition, between the old wood and the bark, of 

 new woody and cortical matter, which in perennial trunks is 

 usually arranged in concentric zones, and traversed by medullary- 

 rays. Leaves furnished with stomata, commonly articulated with 

 the stem, their veins branching and reticulated. Floral enve- 



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