POLLINATING AGENTS 115 



escence is in the form of an easily movable catkin 

 or spike (Maize). 



Wind-flowers are usually dichogamous or diclinous, 

 so that self-pollination is out of the question. For 

 example, all Gymnospermia, such as Pines, Firs, 

 Cycads, &c., are dioecious or monoecious, and wind- 

 pollinated. Their pollen-grains are often provided 

 with wings or air-sacs, which serve to enhance their 

 buoyancy and thus keep them drifting in the air for a 

 longer time than would otherwise be the case. These 

 floats and wings also serve as a steering-gear in the 

 air. As pollen-grains are spoilt by moisture, they are 

 produced and contained in these plants in the exca- 

 vated dorsal surface of the staminal leaves (see fig. 

 279). Similar and various devices for the protection 

 of the pollen are to be seen in flowers. Papaw (see 

 fig's- 77, 78) is a dioecious plant, with large white 

 sessile female flowers, two or three in number, 

 clustered in the axil of a leaf, and small white male 

 flowers, innumerable in number, arranged in long 

 pendulous spikes. The ovary is large, and the sessile 

 radiating branched stigma protrudes out of the 

 corolla-tube. The flowers possess the characters of 

 wind-flowers, and are, in fact, pollinated by wind 

 agency. Pituli {Trewia nudiflora) is a common dioe- 

 cious tree possessing all the characters auxiliary to 

 wind-flowers; it sheds its leaves at the time of flower- 

 ing, so that the exposed long hairy stigmas have every 

 possible chance of catching the drifting pollen-grains. 

 The Grasses, with exserted stamens, versatile anthers, 

 and branched feathery stigmas afford good examples 

 of wind-flowers. Most Juncacece (Rushes or shar), 

 Sedges, Palmacece, Chenopodiacece, and Rumex are 

 familiar examples of wind-flowers. Many of our 

 common fruit trees, such as Mango, amrha, Litchi, 



