MONOCOTYLEDONS AND DICOTYLEDONS 



257 



the stamens are indefinite in number (two to thirty), and 

 the pistil is syncarpous (two carpels). The stamens and 



Fig. 240. Flower clusters of willow (amenta: that to the left is pistillate, the other 

 stamina te. — After Warming. 



pistils are not only separated in different flowers, but upon 

 different plants, some plants being staminate and others 

 pistillate (Fig. 240). The flowers are clustered upon a long 

 axis, and each one is 

 protected by a promi- 

 nent bract. It is these 

 scaly bracts which 

 give character to the 

 cluster, which is called 

 an ament or catkin, 

 and the plants which 

 produce such clusters 

 are said to be amenta- 

 ceous. These aments 

 of poplars, "pussy 

 willows," and the 

 alders and birches are 

 very familiar objects 

 (Figs. 240, 241). 



Fig. 241. Aments of alder (Alnus) : a, branch 

 with staminate aments (n), pistillate amenta 

 (m), and a young bud (ifc); b. pistillate ament at 

 time of discharging seeds, showing the promi- 

 nent bracts.— After Warming. 



