4 oo THE FAGALES 



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, mg) . The flowers are imperfect and the two kinds of sporo- 

 phylls are usually developed upon the same plant. Several bracts 

 are usually associated with sporophylls (Figs. 298, B-F \ 299, 

 B-E) so that the flowers are of a higher type than the willows. 

 The innermost of these bracts is often of a delicate structure and 

 has been referred to as a primitive form of the calyx (Fig. 298, 

 B, pr) and when present in the pistillate flowers it adheres to 

 the ovary (Figs. 298, E, pr; 300, B, pr). The pistils are pro- 

 vided with long delicate stigmas and are compound, containing 

 several ovules but only one usually matures. The wall of the 

 ovary develops into a tough coat about the seed, forming a fruit 

 known. as the nut. Certain bracts of the flower increase greatly 

 in size as the ovary matures and form a conspicuous part of the 

 fruit. Thus in the hornbeam (Fig. 298, D), one of the bracts 

 develops into a large, three-lobed green leaf, in the hop horn- 

 beam the bract forms a papery sac about the nut, in hazel a 

 leafy husk (Fig. 298, F), in the birch and alders a woody peg- 

 like structure. In the chestnut and beech the pistils are com- 

 pletely enveloped by prickly bracts or outgrowths that form the 

 bur (Fig. 300, A-C), while in the oak these structures only cover 

 the lower portion of the ovary, forming the cup ( Fig. 299, CE ) . 

 The flowers of this order are typical of that great group of plants 

 comprising about one tenth of all the flowery plants, which are 

 called anemophilous. Note the small and simple flowers, absence 

 of showy perianth, nectar, and odor glands, dry and light micro- 

 spores lavishly produced to ensure crossing and the delicate 

 bushy stigmas for catching the spores. The stigmas appear a 

 day or so before the adjoining microspores are being shed so 

 that a crossing from an earlier flowering plant is necessitated. 

 These plants form the larger part of our deciduous forests and 

 their association in colonies is doubtless connected with their 

 anemophilous habit, as is also the appearance of the flowers before 

 the leaves are fully developed. The positions assumed by the 

 staminate aments is of service in protecting the microspores 

 against wetting and also to assist in their distribution. During 



