CHAPTER II 



but cultivated plants, that is, plants that have been propagated artifi- 

 cially, are usually not so well adapted to care for themselves as native 

 plants or hardy weeds. On the other hand, plants that are prized 

 because of the food stored in their seeds grow rapidly ; so the time- 

 honored bean or pea and corn are not likely to be supplanted for 

 school room uses. The morning glory is suggested because the 

 embryo has cotyledons even more leaf-like than the castor bean ; but 

 the seed is so small that the seedlings are slow to develop the next 

 leaves. The difference between seeds with and without endosperm 

 is by no means a fundamental one. The common bean and the 

 squash cotyledons have simply absorbed the seed food before enter- 

 ing on the resting stage ; the cotyledon of the castor bean and corn 

 absorb it during germination. 



Nasturtium seeds are very easily grown in the school room in our 

 climate. Ivike the pea, they keep their seed leaves underground, 

 though they do not seem to need this protection so much since their 

 pungent taste probably protects them from the attacks of animals. 

 The wrinkled coat of the nasturtium seed helps to anchor it so that 

 the radicle more easily penetrates the soil. The glutinous envelope of 

 squash seeds serves the same purpose ; so do the hooks of the bur 

 clover, for the seeds usually remain in the bur. Acorn and walnut 

 seedlings always appeal to children. The uses of the cotyledons of 

 the acorn should be developed. They protect the rest of the embryo 

 and liberate it from the shell, besides supplying it with food. The 

 walnut cotyledons contain much oil and the seeds are well protected. 

 On the tree the "shells " or ovary walls are an inconspicuous green 

 color and are extremely bitter ; later, on the ground the shells are 

 again the color of their environment and are still troublesome to 

 marauders. 



The corn seedling presents some difficulties, but it is so convenient 

 for use in experiments that it is introduced here. A considerable 

 quantity should be grown for use in connection with the next chapter. 

 Children need not be told that the kernel is ovary as well as seed, and 

 that some botanists call the absorptive organ the scutellum. The 

 main point is that they understand the functions of the parts. As 

 children become interested in growing seedlings they are likely to 

 make interesting discoveries. They may find barley heads with every 

 seed germinating in its husk, or seeds germinating inside lemons or 

 squashes, and they will see that the lemon seeds have several embryos 

 within one seed coat. They will soon learn to recognize common 

 out-of-door seedlings like the filaree, malva, bur-clover, grasses, 

 mustard, nettles, geraniums, marigolds, etc. The little arrow-head 



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