i62 FERN GROWING 



were formerly considered as only forms of N. Filix-mas until 

 Mr. WoUaston pointed out the specific differences. The 

 great difficulty of crossing any two of these, proves them 

 to be species. From many sowings the author raised only 

 three plants, whilst a portion of the spores (from the same 

 papers) when sown separately produced a great number of 

 plants. 



The largest plant of Nephrodium abbreviatum, that the 

 author has found was growing near the summit of Ben Lawers, 

 not much under the height of four thousand feet. A number 

 of very distinct varieties of this species have been found in the 

 EngHsh Lake district. 



Nephrodium, spinulosum, N. alpinum, and N. cemulum are, 

 according to some authorities, three distinct species, but 

 according to others are only forms of N. s'binulosum. There 

 seems to be a close affinity between the first two, N. alpinum 

 being a dwarf mountain form of N. spinulosum-. As regards 

 N. cemulum, the fronds are quite different, they are so tough 

 that they are only broken with difficulty ; whilst the others 

 have very brittle fronds. N . (sm,ulum, is also a mountain form. 

 In a hilly wood at Hackness, the basal half was, twenty years 

 ago, crowded with N. spinulosum,, which at the bottom of this 

 hill were of an unusual large size ; higher up they became 

 smaller, and then a few plants of N. cemulum. were found 

 amongst them ; higher up N. czmulum, was more abundant, 

 and N. spinulosum, in much diminished numbers ; and at a few 

 feet higher than this the N. spinulosum, ceased, and a large 

 number of N. czmulum seemed to take exclusive possession. 

 The author removed a large number of plants of the N. cBmulum, 

 but yet left thousands. These were planted in two large beds 

 in which there was a liberal supply of half-decayed leaves, in 

 which the plants flourished, and grew into much larger speci- 

 mens than any that could have been gathered at Hackness. 

 These were exclusively N. czmulum, but in the second year 



