POLLINATION 



133 



212. Staminate catkins of oak. The pistil- 

 late flowers are in the leaf ;txils, 

 and not shown in this picture. 



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

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

 ( " in one house " ) . When 

 they are on different plants 

 (poplar and willow, Fig. 

 213), the plant is dioecious 

 ("in two houses")- Monoe- 

 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 flowers 

 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 ;i few pistillate flowers 



are borne in the tassel and a 

 few staminate flowers on the 

 tip of the ear. 



2G9. Although most flowers 

 are of such character as to 

 Insure or Increase t he chances 

 of cross -pollinat ion, there are 

 some which absolutely t<>rl>i<l 

 crossing. These flowers are 

 usually borne beneath or on 

 the ground, and they lack 

 showy colors and perfumes. 

 Tiny are known as cleis- 

 togamous flowers (meaning 



n' plant has norma] slio\v\ flowers 



Llinated, ami in addil ion is pro^ ided 







213. Catkins of a willow. A. staminate 

 flower li show d hi s, and pi^i II 

 late flower al /. The staminate 

 and pistillate are on different 

 plants. 



"hidden flowers"). 



whieh may be inseel 



