52 WAYSIDE AND WOODLAND FERNS. 



may be a simple forking so that the frond ends with two tips, 

 or the branching may be carried to such an extent that there 

 are twenty tips, or any intermediate number. Sometimes the 

 division starts with the stipes, so that two or more fronds are 

 developed from one bud. Under cultivation this tendency to 

 variation has run riot, and there are lists of hundreds of 

 such abnormalities, some of them exceedingly remarkable in 

 character. 



The sori appear in pairs at right angles to the rachis, being 

 produced from contiguous veins. The narrow greenish-white 

 indusia open opposite each other, and at first appear to be 

 double ; but as development of the sori proceeds the indusia 

 are pushed farther apart and their distinctness is made obvious. 

 The spores are amongst the most easy to germinate in a covered 

 seed-pan. The young plants have the first half-dozen or so of 

 their fronds more or less oval or kidney-shaped, but gradually 

 tend towards the strap-shape with each successively new frond. 

 The unrolling adult fronds are prettily coated with silvery hair- 

 like scales, and whatever may be the future inclination of the 

 frond they all start their expansion in a perfectly erect attitude. 



The Hart's-tongue, though very widely distributed throughout 

 these islands, is only locally abundant ; and in vertical range it 

 does not appear to attain a greater altitude than about 600 feet 

 above sea-level. Its distribution outside Britain is throughout 

 Europe from Scandinavia southwards, North Africa, the Azores, 

 Western Asia, Japan, and North-western America. 



Like the Scale Fern it has been richly endowed with names 

 which vary with localities, but the resemblance of its frond to 

 the shape of the tongue in certain mammals is the ruling 

 idea in these names. In this category we find Hart's-tongue, 

 Hind's-tongue, Fox-tongue, Lamb's-tongue, Horse-tongue, and, 

 in Devonshire, Adder's-tongue, though this rightfully belongs 

 to Ophioglossum. Then there are the descriptive Long-leaf, 

 and Buttonhole, the latter suggested by the raised lines of the 



