6B 



HOW PLANTS ARE PROPAGATED. 



corolla-leaves, and the inner corolla-leaves change gradually into stamens, — show- 



ijng that even stamens answer to leaves. 



198". How a stamen answers to a leaf, according to the botanist's idea, Fig. 



i58 is intended to show. The filament or stalk of the stamen answers to the 



footstalk of a leaf; and the anther answers to the blade. The lower part of the 



figure represents a short filament, bearing an anther which 



has its upper half cut away ; and the summit of a leaf is 



placed above it. Fig. 159 is the whole stamen of a Lily 



put beside it for comparison. If the whole anther corre- 

 sponds with the blade of a leaf, then its two cells, or 



halves, answer to the halves of the blade,- one on each side 



of the midrib ; the continuation of the filament, which con- 

 nects the two cells (called the covnective), answers to the 



midrib ; and the anther generally opens along what answer 



to the margins of a leaf. 



199. It is easy to see how a simple pistil answers to a 



leaf. A simple pistil, like one of those of the Stonecrop 



(Fig. 154, 156) is regarded by the botanist as if it were 



made by the folding up inwards of the blade of a leaf, 



(that is, of what would have been a leaf on any branch of the common kind,) so 



that the margins come together and join, making a hollow closed bag, which is the 

 ovary ; a tapering summit forms the style, and some part of the 

 margins of the leaf in this, destitute of skin, becomes the stig- 

 ma. To understand this better, compare Fig. 160, represent- 

 ing a leaf rolled up in this way, with Fig. 156, and with Fig. 

 161, which are pistils, cut in two, that the interior of the ovary 

 may be seen. It is here plain that the ovules or seeds are at- 

 tached to what answers to the united margins of the leaf. The 

 particular part or line, or whatever it may be, that the ovules 

 or seeds are attached to, is called the Placenta. 



200. Varieties or Sorts of Flowers. Now that we have learned 



pjan of Pi.t.i. j^^.^ greatly roots, stems, and leaves vary in their forms and 



appearances, we should expect flowers to exhibit great variety in different species 

 In fact, each class and each family of plants has its flowers upon a plan of its 

 own. But if students understand the general plan of fiowers, as seen in the 



158 159 



Plan of a Stamen. 



