88 THE BOOK OF NATURE STUDY 



in damp places it prefers fairly dry and well-drained soil. The 

 creeping stem is slender, dark-brown or blackish, and bears 

 orange scales, which are continued a little way up the leaf -stalk. 

 The latter is four to twelve inches long, while the upper leafy 

 part is about the same length, and nearly as broad at the base. 

 The leaf is divided into three branches which are stalked and 

 triangular in outline, the two basal branches being smaller than 

 the central one. The central division has its branches equal 

 in size on each side, while in the lower pair of divisions the 

 branches are larger on the lower side of the stalk. The leaf is 

 smooth, soft, and bright green. The spore-masses are rounded, 

 dark brown, small, and scattered over the whole under side of 

 the leaf. The leaves lie down each year. The young leaf, when 

 so far unrolled that the three branches are free, resembles three 

 little green balls at the ends of three branches of a wire. 



It is interesting to compare the habitats and adaptations 

 of these two polypodies. The feathery leaves of the oak fern 

 enable it to grow in deeply shaded places, often among other 

 plants which tend to overshadow it. The leaves are thin and 

 delicate, unable to withstand exposure to sun and wind, and 

 they are annual, developing in spring and dying down in autumn. 

 On the other hand, the common polypody, with its less divided, 

 leathery, evergreen leaves, is able to grow in such exposed places 

 as wall-tops and tree trunks, its leaves lasting during the winter 

 so as to catch the light on bright spring and autumn days when 

 the trees are bare. The oak fern is easily cultivated, if it be 

 given shade and well-drained leaf-mould ; like polypody, it is 

 readily propagated by cutting the stem. 



The commonest of our woodland ferns is the Male Fern 

 (Nephrodium Filix-mas), which is very easily recognised by its 

 robust habit, and above all by the peculiar kidney-shaped scales 

 which cover the clusters of sporangia on the under side of the 

 leaflets. The stem is thick and woody, covered with scales and 

 the crowded bases of old leaves ; the wiry black roots arise from 

 the leaf-bases, not from the stem itself. The leaves are deciduous, 

 dying down in autumn, but leaving their withered bases on the 

 stem, and vary in length from six inches in stunted plants to four 

 or five feet in especially robust ones. The stem grows at or just 



