18 PRIMARY DIVISIONS OF THE VEGETABLE KINGDOM. 



66. These Grand Divisions are further distinguished by their 

 organic structure and general aspects. In the Phajnogamia we find a 

 system of compound organs, such as root, stem, leaf, bud, flower, suc- 

 cessively developed on a determinate plan ; while in the Cryptogamia, 

 a gradual departure from this plan commences, and they become, at 

 length, in their lowest forms, simple expansions of a uniform tissue, 

 without symmetry or proportion. This distinction is rendered perfectly 

 clear by a reference to 



67. Examples. Compare a rose with a fern. In the former a regular axis 

 bears buds which are unfolded, soma into leaves, others into flowers succeeded by 

 fruit. In the fern no buds nor Dowers appear, and the fruit dots sprinkle over the 

 back of the leaf. Again, contrast the violet with a lichen, where neither stem, root, 

 nor leaf appears, much less flowers, but disc-Iiko expansions with fruit-dust (spores) 

 produced indifferently in any part of them. 



68. Subdivisions op the Ph^nogamia. This grand division is 

 itself voiy naturally resolved into two subdivisions, named by De Candolle 

 Exogens and Endogens. 



69. Exogenous plants or Exogens (outside-growers), including all 

 the trees (except palms) and most herbaceous plants of temperate regions, 

 are so named, because the additions to the diameter of the stem are 

 made externally to the wood already formed. 



70. Endogenous plants or Endogens (inside-growers), including the 

 grasses and most bulbous plants of temperate climates, and the palms, 

 canes, £tc., south, are so named from the accretions of the stem taking 

 place within the parts already formed. 



71. These subdivisions are more accurately distinguished by the 

 structure of the seed. The seeds of the Exogens consists of two equal 

 seed-lobes, called cotyledons, as seen in the pea. The seed of the Endo- 

 gens consists of but one seed-lobe or cotyledon, as in the Indian Corn. 

 On this account Exogens were first called Dicotyledonous (two-cotyle- 

 doned) plants, and Endogens, Monocotylcdonous (one-cotyledoned) 

 plants ;— names quite appropriate, but too hard and long for general use. 



72. They are also very readily distinguished by their leaves, 

 which are net-veined in the Exogens, and parallel-veined in the Endogens. 

 Moreover, their flowers arc remarkably different, being almost alwayp 

 three-parted in the latter and about five-parted in the former. But all 

 these distinctions, with some others,will be more definitely stated hereafter; 



73. The Name of a *>lakt or other natural object is twofold, — the trivial or 

 popular name, by vrfiich it is generally known in the country ; and the Latin name, 

 by which it is accurately designated in science throughout the world. For example , 

 slrawbeiTy is the popular name, and Fragaria vesca the Latin or scientific name of 

 the samp plant. 



74. In elementary treatises, like the present, for the sake of being readily under- 

 Btood, plants are usually called by their popular names. Yot wo eame.stly recom- 

 mend to the learner to accustom himself early to the use of the more accurate names 

 employed in science. 



