18 PRIMARY DIVI8I0NS OF THB VEGETABLE KINGDOM. 



66. These Grand Divisions are further distinguished by thdn* 

 organic structure and general aspects. In the Phsenogamia 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 

 <;lear by a reference to 



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

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

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

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

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

 produced indifferently in any part of them. 



68. Subdivisions or the PH.aEN0GAMiA. This grand division is 

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

 Exogens and Endogens. 



69. Exogenous plants or Exooens (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, amd the palms, 

 canes, etc., south, are so named from the accretions of the stem tating 

 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, Monocotyledonous (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 are remarkably different, being almost always 

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

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



73. The Name op a plant or other natural object is twofold, — the trivial or 

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

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

 strawberry is the popular natne, and Pragaria vesca the Latin or scientiflc name of 

 the g.ime plant. 



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

 stood, plants are usually called by their popular names. Yet we earnestly recom- 

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

 employed in science. 



