^^ 



J 



DEVELOPMENT OF PLANTS 431 



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

 pistil is simple (Fig. 297, Z)). 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 leaves become large and so interfere with the 

 distribution of the microspores are all characteristics of wind polli- 

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

 are developed in the flowers of the willow (F'ig. 297, D, n) and 

 that the microspores are sticky. Perhaps we have here an illus- / 



tration of one of the earliest variations of the flower thai served asl- 



-4Jie_DEctar iriands 



\ 



an allurement to insects. Certaiii l^, tho n^rtar_^gm.nds and the \ 

 conspicuous display of microsporophylls are a very efficient 

 attraction, as is attested by the variety of insects that swarm 

 about the aments. 



The most efflcient factor in the distribution of the willows and 

 poplars is found in the seed. The pistils 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, J). 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 . ^ U 

 distance and cover everything in the neighborhood of the trees \ \^v^ 

 with their lint-like masses. The name cottonwood is popularly ^*v^ 

 applied to several of the poplars because of the cotton-like clusters 

 of seeds that emerge from their aments. 



139. Fagales, the Beech Order. — This order includes many 

 of the most important hard-wood trees of the temperate regions, 

 comprising the family of the birches, with such representatives 

 as the American hornbeam (Carpimis), hop hornbeam (Ostrya), 

 hazel (Corylus), birch (Betula), alder (Abius) and the beech 

 family, which includes the chestnut {Castanca), beech (Fagus) 

 and oak {Ouerciis). The inflorescence is more commonly an 

 anient as in the preceding order (Figs. 298, A ; 299, A), although 

 in the hazel and in the beech family only one or a few pistils are 

 developed in the bud-like clusters of overlapping bracts (Fig. 

 299» P)- The flowers are imperfect and the two kinds of sporo- 



