39 8 THE SALICALES 



a compact inflorescence known as an ament or catkin (Fig. 297, 



C, E). The distinguishing feature of this kind of flower cluster 

 is seen in the scale or bract that protects each flower (Fig. 297, 



D, F). The aments and also the leaves are concealed in buds 

 that are peculiar in that they are protected by a boat-shaped 

 scale (Fig. 297, A). These plants flower very early in the spring 

 and as the ament emerges from the bud the overlapping bracts 

 with their hairy coats form the " pussy willow " stage of the 

 inflorescence (Fig. 297, B). Soon the bracts spread apart, ex- 

 posing the flowers which are nearly as primitive as the simplest 

 of the monocotyledons, being without perianth, imperfect and 

 usually the two kinds of sporophylls are arranged on different 

 plants. The pistil is compound and composed of two carpels, 

 each of which contains numerous ovules, so that the pistillate 

 flowers are not as primitive as those of the cat-tails, where the 

 pistil is simple (Fig. 297, D). The staminate flowers show the 

 same .primitive characters (Fig. 297, F), consisting of one or 

 more naked stamens. The absence of showy perianth, the ex- 

 travagant production of microspores and the formation of the 

 flowers before the leave.s become large and so interfere with the 

 distribution of the microspores are all characteristics of anemoph- 

 ilous flowers. It is noteworthy, however, that nectar glands 

 are developed in the flowers of the willow (Fig. 297, D, n) and 

 that the microspores are sticky, indicating that these flowers are 

 entomophilous. Perhaps we have here an illustration of one of 

 the earliest variations of the flower that served as an allurement 

 to insects. Certainly, the nectar glands and the conspicuous dis- 

 play of microsporophylls are a very efficient attraction, as is at- 

 tested by the variety of insects that swarm about the aments. 



The most efficient factor in the distribution of the willows and 

 poplars is found in the seed. The megasporophylls mature in the 

 early summer, when the two carpels spread apart (Fig. 297, 

 G-I), permitting the discharge of the seeds, which are provided 

 with a circle of hair at the base (Fig. 297, /). This parachute 

 is not so nicely constructed as in Typha, but it is so efficient 

 that myriad numbers of minute seeds are carried a considerable 

 distance and cover everything in the neighborhood of the trees 



