416 



STRUCTURE AND LIFE HISTORIES 



ascertained by observing the oldest annual growth still 

 bearing spur-shoots. When the leaves are shed the 

 entire spur-shoot falls away. 



Reproduction 



370. Staminate Cones. Most of the cone-bearing trees 

 (Coniferae) are monoecious, i.e., bear both microspores 

 and megaspores on the same tree. The staminate cones 

 appear in the spring, usually in May in the northern states, 



FIG. 306. Staminate cones of the Austrian pine (Pinus austriaca). 

 Helow, before shedding pollen; above, after shedding. 



and persist for only a few weeks. They are borne in 

 clusters on the long branches on the current year's growth, 

 and occupy the lateral position of spur-shoots; they are 

 never terminal (Fig. 306). They are, in reality, modified 



