A MANUAL OF BOTANY 47 



reference to the presence of water or moist ground. Observe 

 the size of the shrubs and the frequency of the yellow- 

 flowered form now to be studied. 



The catkin. Examine the " j^ussies " as they grow on the 

 willow tree or shrub, and observe that, as stated in the note, 

 there are two forms borne on separate plants. What 

 feature easily distinguishes the one kind from the other? 

 The technical name for the flower clusters is catkin. What 

 relation does this bear to the common name " pussies " ? 



Examine a staminate catkin and observe its form and 

 color. To what is the color due? 



The small leaves at the base of the catkin are bracts. 

 Observe the catkin in detail and find out what structures 

 make up its bulk. Does the catkin appear with, after, or 

 before the leaves? Draw the catkin, natural size or slight- 

 ly enlarged, as it is attached to the stem. 



The flower. Examine an individual structure or part of 

 this catkin (jioicer) (m). It consists of a dark scale, bearing 

 one or two slender, knobbed stalks (stamens). What is 

 peculiar about the scale, and what use has this peculiar 

 feature? Draw a staminate flower. 



The stamen. Examine a stamen (??i) and (?/)) and find the 

 slender stalk (Jilament) and the top enlargement (anther). 

 What color is each? Draw a stamen (m) and (Z^)). 



Pollen. Crush an anther on a slide, mount in water, and 

 examine (hj)). Observe the pollen grains (microspores). 

 What is their form, color, and number. Draw several. 



Examine pollen grains that have been in water for a 

 couple of hours and observe that some show sprouts (ger- 

 mination). Remember this, as it will be referred to 

 later. 



Count the number of catkins on a well-grown branch, also 

 the number of flowers for an average-sized catkin. From 

 this count form some idea of the amount of pollen produced 

 by a single willow. Why is there such an enormous pro- 



