ORIGIN AND DEVELOPMENT OF SOME COMMON 



FRUITS. 



Frederick C. Newcombe, Ph.D., Jr. Prof, of Botany, University of Michigan. 



AN is not content to see the 

 outside of things. It is not 

 enough for some of us that 

 we can recognize apples 

 and grapes as such, but we wish to 

 know how these things come to be, how 

 they originate and how they develop. 

 We are to consider for a few moments 

 the origin and development of a few of 

 our common edible fruits. 



We all know that the flower precedes 

 the fruit, and before we can talk of the 

 origin of the fruit we must look to the 

 structure of the flower. In Fig. 15 19 is 



ISTIL 



"A MENS 



COROLLA 



CALYX 

 -STEM 



FIG. 1519.— Diagram of a flower in longitudinal 

 section. 



shown a diagrammatic view of a longi 

 tudinal section of a complete flower. 

 The parts of the flower are seen to arise 

 in circles from the flower stem, the 

 lowest circle being the calyx, the nex 

 above the corolla, then the stamens, and 

 sitting on the apex of the stem is the 

 pistil. The calyx is usually green, and 

 surrounds the stem as a cup or as severa 

 small leaves ; in the bud it is folded 

 closely over the other parts within, often 

 protecting them by a waxy covering 

 from the intrusion of rain, and from 

 bird or insect enemies by distasteful 



secretions. The showy corolla which to 

 man's eye paints nature in beautiful 

 colors, is a sign unfurled by the plant to 

 tell insects of good things to eat, of 

 banquets of pollen and nectar. The 

 stamens with slender stalks supporting 

 pollen-sacs are the male organs whose 

 pollen-grains effect the fertilization of 

 the ovule and thus start the growth of 

 the fruit. The pistil is the female organ 

 containing in its flask-shaped base, or 

 ovary, the ovules which are the germs of 

 seeds. 



This is the structure of a simple and 

 complete flower. But every part just 

 named is capable of modification, and 

 there is no part among those named 

 that may not be absent from some 

 species of flowers. In the pea and the 

 bean flower, for instance, the corolla is 

 so modified that its separate leaves are 

 no longer all alike, but together present 

 a peculiar butterfly appearance. In the 

 pumpkin the corolla is all in one piece 

 forming a beautiful yellow funnel. The 

 corolla may, instead of one, be com- 

 posed of several rows of colored leaves, 

 as in the cultivated rose or the white 

 water lily. On the other hand, the 

 corolla may be wholly absent, as in the 

 flowers of the sugar maple ; the calyx 

 and corolla may both be absent as in 

 our American sycamore and in the 

 female flowers of the birch ; the stamens 

 may be absent as in one kind of flowers 

 in the melons, or the pistils may be 

 absent as in the other kind of flower of 

 the melons. When all parts are present 

 in a single flower, the pistils and stamens 

 may become mature at different times, 

 thus insuring cross-fertilization, as in the 

 pear. The successful fruit-raiser takes 



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