POLLINATION 



133 



n2. 8tamin;ite catkins of oak. Tlie pist 

 late flowers are in tlie leaf axi 

 and not shown in this picture. 



flowers are on the same plant, e. g., oak (Fig. 212), bcocli, 

 chestnut, hazel, walnut, hickory, the plant is moncecious 

 ("in one house")- When 

 they are on different plants 

 (poplar and willow, Fig. 

 213), the plant is dioecious 

 ("in two houses"). Mona'- 

 cious and dioecious plants 

 may be pollinated by wind 

 or insects, or other agents. 

 They are usually wind -polli- 

 nated, although willows are 

 often, if not mostly, insect- 

 pollinated. The Indian corn 

 (Fig. 214) is a monoecious plant. The staminate flowei-s 

 are in a terminal panicle (tassel). The pistillate flow- 

 ers are in a dense spike (ear), inclosed in a sheath or 

 husk. Each "silk" is a style. Each pistillate flower pro- 

 duces a kernel of corn. Sometimes a few pistillate flowei-s 

 are borne in the tassel and a 

 few staminate flowers on the 

 tip of the ear. 



269. Although most flowers 

 are of such character as to 

 insure or increase the chances 

 of cross -pollination, there are 

 some ivJiich absolutely forbid 

 crossing. These flowers are 

 usually borne beneath or on 

 the ground, and they lack 

 showy colors and perfumes. 

 They are known as cleis- 

 togamous flowers (meaning 

 lilt has normal showy flowers 

 which maybe inseet-pollinated, and in addition is provided 



2i:j. Catkins of a willow. A staminate 

 flower is shown at s, and a pistil- 

 late flower at p. The staminate 

 and pistillate are on different 

 plants. 



"hidden flowers"). The i 



