NAMED, AND STUDIED. 97 



Flowerixg on Ph^exogamous Plants, namely, those that are propagated 

 by means of real flowers, producing seeds, which contain an embryo ready formed. 

 The lower series consists of 



Flowerless or Cryptogamous Plants, which produce no real flowers and 

 no true seeds, but only something of a simpler sort, answering to flowers and giv- 

 ing rise to spores, which, serve the purpose of seeds. 



309. This has been explained in Chapter 11. Section II. p. 58. Next, the 

 great series of Flowering Plants is divided into two Classes. These classes are 

 distinguishable by the stem, the leaves, the flower, and the embryo or germ of the 

 seed. They are : — 



Class I. Exogens, or Dicotyledons (more fully named, Exogenous or Di- 

 cotyledonous Plants). Plants of this class, as to their stems, have the wood all 

 between a separate pith in the centre and a bark on the surface, and each year the 

 stem lives, it forms a new^ layer of wood on the surface of that of the previous year 

 (111, 115 — 118). As to the leaves, they are netted-veined or reticulated, the veins 

 branching and forming meshes (12G, 127). As to the jioivers, their parts are gen- 

 erally in fives or fours (or the double or treble of these numbers), very rarely 

 in threes. As to the embryo, or germ, it always has a pair of cotyledons or seed- 

 leaves (48), or sometimes more than a pair (49). 



Class 11. Endogens, or Monocotyledons (or more fully, Endogenous or 

 Monocotyledonous Plants). Plants of this class, as to their stems, have their wood 

 in threads mixed with the pith and scattered throughout every part, never forming 

 layers, and the bark is never to be peeled off clean from the wood (112 — 114). 

 The leaves are almost always parallel-veined (127 — 129). The Jioivers have their 

 parts in threes (or twice three), very rarely in twos or fours, never in fives, which 

 is much the commonest number in the other class. And the embryo has but one 

 cotyledon or seed-leaf (47, 50). 



310. So the class of any plant may be told from a piece of its stem alone; or 

 from a single leaf, in most cases ; or from a blossom ; or from a seed ; or from the 

 ])lantlet as it springs from the seed, and in its first leaves shows the nature of the 

 embryo. The seeds generally are not easy to study without a dissecting micro- 

 scope, nor can we always have them growing. But the student will hardly ever 

 fail to tell the class at once, by the stem, the leaves, or the flowers, and by the 

 whole look of the plant. 



311. The first Class divides into two Subclasses, of very unequal size, viz. : — 



