Ch. VI, 2] 



STRUCTURE OF FLOWERS 



273 



When the same in numlier with the petals, the stamens 

 usually alternate therewith, thougii they stand opposite in 

 Primrose (Fig. 201). Flowers also occur without stamens, 

 or rather, to be exact, with the stamens and pistils in 

 separate flowers. 



Beyond the stamens, and occupying the center of the 

 flower, come the pistils, made up of parts called cahpels, 

 which, like sepals, petals, and stamens, are morphologically 

 leaves. The Peony here picturetl (Fig. 183) shows two 

 pistils composed each of a carpel ; and of one carpel each are 

 the many pistils of Buttercup and Strawberry, while Peas 

 and Beans have one pistil composed of one carpel. Most 



Fig. 186. — Typical forms of nectaries. From the left ; spurs of Toad- 

 flax, receptacular swellings of Grape, spurs of ColumlDine, scales on the 

 petals of Ranunculus. (From Bailey.) 



commonly, however, there is one pistil composed of several 

 united carpels. Whether sijiple (of single carpels), or 

 coiiPOUND (of several carpels united), the pistil has tj-pically 

 a rounded hollow base called the ovahy, tapering upward 

 to a short cylindrical stalk called the style (very short in 

 the Peon}'), ending in a roughened area called the stigma. 

 When the ovary is opened, it is found to contain a number 

 of small rounded whitish bodies called ovules, within 

 each of which, in a special sac, lies a female sex cell, called 

 the egg cell. The functions of the parts of the pistil are 

 plain ; the stigma receives the pollen containing the male 

 cells, the st^de supports the stigma in a position suitable 

 for receiving the pollen, and the ovary protects the deHcate 



