668 FAMILIES OF ANGIOSPERMS. 



flower are present? How many stamens in a flower? If a hand lens is 

 convenient, use it in making out the form of the parts. Sketch a flower in 

 its position on the axis of the catkin, showing also the bract at the base of 

 the flower. Describe the character of the bract as seen under the lens. 



The pistillate catkin. What parts of the flower are present? Compare 

 with the staminate flower. Sketch a pistillate flower with the subtending 



Fig. 555- 

 Spray of willow leaves, pistillate and staminate catkins (Salix discolor;. 



bract to show the form of the ovary, with the divided stigma. Is the pistil 

 sessile or stalked? How many carpels make up the pistil? Is there a 

 small gland (nectary) present near the base of the ovary which represents 

 the perianth? Is there a nectary on the staminate flower? 



The fruit. Examine ripe pods of the willow. Determine what parts 

 of the flower unite to form the fruit. What difference between a fruit and 

 seed in the willow? What means is provided for the dissemination of the 

 seeds? 



Field observations on the willows. At what time do the catkins of the 

 willow appear? Do they flower before the leaves appear? At time of 

 flowering note the character and abundance of the pollen from the stamens. 

 Is it in the form of "dust," or is it adhesive? How are the willows 

 pollinated ? Do insects visit the willow flower ? Are willows easily prop- 

 agated by shoots ? What happens if a willow branch is stuck into damp 

 soils; when it is left in the water for some time? 



