68 PLANTS AND MAN 



flower is the catkin (fig. 40), a cone-like reproductive organ of 

 which the hairy "pussy" of the willow is representative. Catkins 

 are usually yellow or green in color and of inconspicuous size; 

 they are the type of flower found on many trees such as the oaks, 

 poplars, willow^s, birches and hickories. Male catkins produce 

 pollen (microspores) in special sporangia-bearing structures 

 known as stamens; while the female catkins develop ovules 

 (sporangia producing megaspores) in highly specialized struc- 

 tures known as pistils. Wind pollination, as in the Gymnosperms; 

 results in the chance transfer of a pollen grain to the pistil, where 



iNDIVfDUAL FLOWERS 



FEMALE (PfSTULAre:) MALS (STAMtNATC) 



Fig. 40. — Catkins are clusters of wind-pollinated flowers which lack conspicu- 

 ously colored floral parts. 



the male prothallus germinates, produces a pollen tube and the 

 union of the male and female cells takes place in the ovule. The 

 seeds develop in the female catkins as in the pine. 



A catkin, however, does not conform to the popular idea of a 

 flower, even though it fulfills the most essential function of a 

 flower — the production of the reproductive cells. Flowers are 

 generally considered to be brightly colored, often fragrant, por- 

 tions of the plant body. This is because many Angiosperms which 

 comprise our woody shrubs, garden and house plants, and 

 orchard trees have come to rely upon another pollination method 

 than that by wind. The transfer of pollen from stamen to pistil is 

 brought about by animals in a more reliable manner; special 



