238 LIFE HISTORY OF A FERN. 



margins of the meshes. The external surface of the stem is 

 thickly covered with the persistent bases of the leaves, and these 

 are densely clothed with brown scaly hairs or ramentse. 



The leaves of Ferns are much slower in their development than 

 those of other plants, for an examination of the stem reveals the 

 fact that two years are occupied in their growth before they appear 

 as mature leaves. Thus, the stem not only bears the persistent 

 bases of older leaves that have died down in former years ; but 

 three generations of growing leaves, one of which is the perfect 

 leaf of the present season, and the others are buds in different 

 stages of development which will arrive at maturity in succession 

 during the ensuing two years. 



Not only in the duration of their growth, but in the manner of 

 their development, the leaves of Ferns differ materially from other 

 orders. A familiar example of this peculiarity may be seen in the 

 young leaves of the Hart's-tongue Fern, which, when first they 

 appear in the spring above the surface of the soil, are beautifully 

 curled up from the tip, like a beautifully-formed crozier, and as the 

 growth advances they are gradually unfolded until the leaf becomes 

 fully expanded. This curling-up of the young leaf, which is 

 termed circinate vernation, is characteristic of all ferns, and in 

 some of the pinnate species assumes very complicated and beau- 

 tiful forms. Ruskin's definition of a leaf is peculiarly applicable to 

 these delicate and lovely unfoldings of the young Ferns. He says 

 it is "the thing that is born " or " put forth." '* When the branch 

 is tender and putteth forth her leaves, ye know that summer is 

 nigh." " It is the springing thing," this thin film of life ; rising 

 with its edge out of the ground — infinitely feeble, infinitely fair. 



It will be observed that throughout we have spoken of leaves 

 rather than fronds, which is their general designation. But modern 

 botanists are of opinion that no material object can be served by 

 the retention of the popular word "frond," inasmuch as they are, 

 equally with the leaves of higher orders of plants, organs of 

 respiration and assimilation, wherein by a vital action those liquid 

 and mineral constituents derived from the soil by the roots, 

 undergo the chemical changes which are needed to fit them for 

 the vegetative processes of the plant. 



It is unnecessary to enter into an examination of the many 



