210 WAYSIDE WEEDS. 



great divisions^ into whicli plants possessing 

 essential flower organs are divided : — 



Plants with one seed-lobe, or cotyledon, mono- 

 cotyledons; plants witii two seed-lobes, di-coty- 



LEDONS. 



Also, from the mode of growth peculiar to each, 

 called endogens and exogens : that is, plants the 

 yearly growth of which takes place by additions to 

 the centre of the stem, the endogen ; or, by addi- 

 tions between the bark and the stem, the exogen. 

 The latter represents the great mass of plants which 

 make up the larger vegetation of our temperate 

 zones, including our forest trees ; the former the 

 tropical vegetation, the palms, the bananas, the 

 bamboos ; but also the grasses and grains, the lilies, 

 snowdrops, and crocuses of northern regions. Our 

 readers may remember that these endogenous or 

 mono-cotyledonous plants are those characterized by 

 straight-veined leaves, and for the most part by a 

 ternary division of the parts of the flower; the 

 exogens, or di-cotyledons, by leaves with interlace 

 ing veins, and no fixed division of the flower organs. 



Leaving behind us the great section of straight- 

 veined, one-seed-lobed, central growing flowering 

 plants, we find the netted-veined, two-seed-lobed 

 exogens, once more divided naturally into three 

 groups : — 



Plants which have the coroUa in many pieces, 

 represented by our old friends the ranunculuses, 

 poppies, etc. 



