22 



HOW PLANTS GROW FROM THE SEED. 



Pea (Fig. 42), and of all such plants, is dicotyledonous, that is, has a pair of 

 cotyledons, or seed-leaves, which is what the word means. Therefore all such 

 plants are called Dicotyledonous Plants. 



49. Pine-trees, and plants like them, generally have more than 

 two cotyledons, in a circle ; so their embryo is said to be poly- 

 cotyUdonous ; meaning " with several or many cotyledons." Fig. 

 49 is a magnified view of a Pine-seed, divided lengthwise, and 

 showing the long and straight embryo lying in the middle of the 

 albumen. The slender lower part is the radicle or stemlet ; the 

 upper part is a cluster of cotyledons or seed-leaves, in a close 

 bundle ; three of them can be seen as it lies, and there are as 

 many more behind. Fig. 50 is this embryo as it comes up from 

 the seed, its cotyledons (six in number) expanding at once into 

 a circle of slender, needle-shaped leaves. 



50. It is a pity these three words are so long; for the pupil 

 should fix them thoroughly in his memory ; because these differ- 

 ences in the embryo, or plantlet in the seed, run through the whole 

 life of the plant, and show themselves in many other differences 



which very strikingly distinguish one class of plants from another. Let it be re- 

 membered, therefore, that 



Monocotyledonous Plants, or Monocotyledons, are those which have only one 

 cotyledon or seed-leaf to their embryo. 



Dicotyledonous Plants, or Dicotyledons, are those which have a pair of cotyledons 

 or seed-leaves to their embryo. 



Polycotyledonous Plants, or Poly cotyledons, are those which have more than one 

 pair of cotyledons or seed-leaves to their embryo. 



Analysis of the Section. 



24. Flowers produce Fruit; this, the Seed; of this the essential part is the Embryo which grows. 

 25. It is alive; but lies dormant awhile. How long seeds may live. 



26. Germination, the beginning of growth; what is needful for it. 27. What takes place, illustrated 

 from the Morning-Glory. 28. How the stemlet grows by lengthening, and carries up the seed-leaves: 

 how the root is formed and gi-ows downwards. 29. Instinct of each part to turn in its proper direc- 

 tion; and why. 30. The little seedling a complete plant in miniature; its parts. 31. How it goes on 

 to grow : growth of the root ; rootlets ; of the stem. The Plumule or Bud. Development of the stem 

 piece by piece, each with its leaf. 



32. How the seedling is nourished at the bep:inning. Growth requires food. 83. How this is sup- 

 plied by a deposit in the seed ; Albumen. 34. It is kept in a solid form until the embryo starts and ia 



