192 . GROWTH AND WORK OF PLANTS 



now elongates, and the brush on the outside of the closed stigma 

 sweeps out the pollen. The stigma now opens, the lobes curving 

 outward so that the pollen does not fall on its upper receptive 

 surface, but the visiting insect brings pollen from another flower. 

 308. Flowers in which the pistils mature first. In the 

 figwort the flower is urn-like, and the mature stigma is thrust out- 

 side of the flower by the long style, while the stamens are curved 

 backward in the flower. When the stigma of this flower is past 

 the receptive stage, the stamens straighten out and bring the 

 anthers to the outside of the flower, where they shed their pollen 



Fig. 144- 



Kalmia latifolia, showing position of anthers before insect visits, and at the right the 

 scattering of the pollen when disturbed by insects. Middle figure section of flower. 



so that a visiting insect can carry it to another flower in which 

 the stigma is receptive. Jn the skunk cabbage the stamens in 

 the flowers of some plants mature first, while in other plants the 

 pistils mature first. 



309. Movements executed by stamens or pistils to aid in 

 cross-pollination. The movements of the pistils and stamens 

 described in the study of the sunflower (paragraph 272) and of 

 the bellflower in the preceding paragraphs are illustrations. A 

 remarkable case is seen in the mountain laurel (Kalmia). The 

 stamens are bent outward and the anthers are held in little pockets 

 near the base of the petals. When the insect is crawling over the 

 flower and touches the stamens, the anthers are released suddenly, 

 fly up and throw the pollen on the body of the insect. The action 

 of the stamens can be seen by touching the filaments with a pencil 



