I 4 4 GROWTH AND WORK OF PLANTS 



the filament. It bears the anther, usually at the top. The anther 

 is the pollen case (spore case, see paragraphs 544, 557). It con- 

 sists of anther sacs, or pollen sacs containing the pollen grains. 

 The stamens are usually separate, but sometimes they are united 

 by their filaments or by their anthers. When the pollen is ripe 

 the sacs open by slits or pores and permit the escape of the 

 pollen. 



227. The pistil. The pistil consists of the "ovary," the 

 style (not always present), and the stigma. These are well 

 shown in a simple pistil, common examples of which are found in 

 the pea, buttercup, etc. The simple pistil consists of a single 

 carpel, while the compound pistil consists of two or more carpels 

 joined, as in the tooth worl, lily, fuchsia, etc. The ovary is the 

 enlarged part of thejDistil which below is attached to the recepta- 

 cle of the flower. It contains the ovules, the structures which 

 ripen to form the seeds. The style, when present, is a slender 

 elongation of the upper end of the ovary. The stigma is usually 

 an enlargement of the end of the style. It sometimes extends 

 down one side, or when the style is absent it is attached to the 

 end of the ovary. A portion of the stigma (the stigmatic surface) 

 is glutinous or "sticky," and serves to hold the pollen grains 

 when they come in contact with it. 



228. Attachment of the ovules or seeds in the ovary 

 (Placentation). The attachment of the ovules or seeds in the 

 ovary can be very easily understood if we remember that the 

 simple pistil, or each division of the compound pistil, is a single 

 carpel, or modified leaf (carpellary leaf). In the simple pistil 

 the carpellary leaf is folded so that the two edges meet and join 

 forming a single closed space, or locule. In such simple pistils 

 as the marsh marigold, pea, etc., the ovules are attached to the 

 edges of the carpel-leaf where they are joined. 



In the compound pistil, the two or more carpel-leaves of which 

 it is composed are united in different degrees, i. The compound 

 pistil with one locule: 



a. Parietal placenta. Here the edges of adjacent carpel-leaves 

 are joined forming an ovule-bearing line (or -placenta as it is 



