coNii-Kk.u. : Tin-. .-< i rrs pine 



533 



As these project at the time of pollination above the end of the • 

 tending shoot, they arc in the best possible position for receiving I 

 wind-borne pollen. The male flower is enveloped below by niembr 

 scales, and bears distally numerous sporophylU or stamen: . h with 



Fig. 420. 



Pinus nigra, Arnold. Shoot bearing mak (lowers in place of 1 



spurs. (After Groom.) 



two pollen-sacs on its under side (Fi-. 4- f, B t C). Th< pollen-grains are 

 peculiar in bearing right and left of the grain itself air-containing sacs 

 (wings) which give a low specific gravity to the whole grain, and so 

 aid its transfer by the breeze (Fig. 421, D). At the tunc when r 

 shed, the grain of Pinus contain.-, in addition to the vestigial remains 

 of two obliterated cells of the male prothallus, one nucleated cell 



