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CHAPTER XVI. 



MONOCOTYLEDONS HYDEOCHAEIDlCEJE OECHID- 

 lEIDXCE^] AMAEYLLIDACE^ DIOSCOEI- 

 LILllCE^] MELANTHlCEJE 



" The Lily of the Vale, of flowers the queen, 



Puts on the robe she neither sewed nor spun ; 

 The birds on ground, or on the branches green, 

 Hop to and fro, and glitter in the sun. 



" Now is the time for those who wisdom love, 



Who love to walk in Nature's flowery road, 

 Along the lovely paths of spring to rove, 

 And follow Nature up to Nature's God." 



WE are now to begin the second great class of plants, the One- 

 loled class (Monocotyledonous). Here the seed-vessel does 

 not split, as in the members of the last class, but germinates 

 from the end. There is a second permanent mark of distinction 

 between the classes in the veining of the leaves, the veins being 

 disposed in a network fashion in the Two-lobed class, and in a 

 parallel one in the One-lobed class. A third point of distinc- 

 tion, and one even more valuable, because it can be examined 

 when seeds and leaves are both absent, is in the stem. The 

 trees of the Two-lobed class increase their wood by concentric 

 layers ; each year a new layer is added, and the whole is en- 

 veloped in the bark. These are called Exogens, because they 

 are outside growers. The bark consists of three parts the 

 outside skin, the solid part, and the inner bark. The two 

 inner parts often increase with such rapidity that the outer 

 cracks ; some trees throw off the bark from year to year. As 

 soon as a tree-seedling begins to grow a few inches high, the 

 centre of the stem becomes pith, and rays extend to the limits 

 of the skin ; then a layer is formed round the pith, and called 

 the sapwood, and layers are continually added to this during 

 all the growth of the tree. 

 Trees of the One-lobed class increase from ivithin, and are 



