360 BRITISH FLOWERING PLANTS 



AMENTACE^ 



This order comprises many of our forest trees — the 

 Oak, Beech, Hornbeam, Birch, Poplars, Willows, etc. 

 The flowers are generally monoecious or dioecious ; they 

 generally precede the leaves. Perianth none, or forming 

 a mere border to the ovary. In some the fruits are 

 winged (Birch), or carried on winged bracts (Horn- 

 beam), or the seeds are provided with silky hairs (Willow, 

 Poplar), and dispersed by the wind, an arrangement 

 especially suitable in the case of trees ; in others (Beech, 

 Spanish Chestnut, Hazel, Oak) they are carried by 

 animals. In several, for instance in the Hornbeam, Birch, 

 Hazel, Willow, etc., as in the case of the Lime {ante, 

 p. 31), the bud situated apparently at the end of the 

 branchlets is in reality axillary, as is shown by the 

 presence of a terminal scar, due to the fall of the true 

 terminal bud. The genera here included in Amentacese 

 are separated in recent systems of classification under 

 the orders Myricacese (Myrica), Corylacese (Alnus, 

 Betula, Corylus, Carpinus), Fagaceae (Fagus, Quercus, 

 Castanea), Salicacese (Salix, Populus). 



In my Flowers, Fruits, and Leaves I have devoted 

 some space to the consideration of the arrangement and 

 forms of the leaves in this family, and it will perhaps 

 be more convenient to consider them here as a group 

 than under the separate species. In the first place, let 

 us consider the size of the leaf. On what does this 

 depend ? In herbs we very often see that the leaves 

 decrease towards the end of the shoot, while in trees 

 the leaves, though not identical, are much more uni- 

 form in size. If we take a twig of Hornbeam, we 

 shall find that the six terminal leaves have together 

 an area of about 14 square inches, and the section 

 of the twig has a diameter of "06 of an inch. In 

 the Beech the leaves are rather larger, six of them 

 having an area of perhaps 18 inches, and correspond- 

 ing with this greater leaf-surface we find that the 



