THE i'OLYSTICHUMS 2 [7 



Wakeleyanum (cruciatum).— Found in S. Devon by Mrs. 

 Wakeley ; pinnae set on in pairs at right-angles, forming crosses with 

 opposite pairs ; one of the parents of Mr. E. J. Lowe's hybridum 

 aculeatum. 



POLYSTICHUM LONCHITIS (THE HOLLY Fern) 



(Plate XXXII) 



This Fern has been named the Holly Fern, owing to the hard, 

 leathery texture of its fronds, and the shape and prickly edges of 

 the pinna or subdivisions. It is purely a mountain Fern, and in 

 Great Britain is never found wild at a lower elevation than 1100 

 feet, most of its habitats being far above that limit, 2000 to' 3000 

 feet. It grows in the chinks of the weathered rocks, or in the "short 

 grass or other growths under their lee. At the 1100 level, near 

 Aberfeldy, we found numerous large plants in rocky soil among the 

 heather, where, at a distance, the projecting, erect fronds were at 

 first taken for the fertile fronds of the Hard Fern (Blechnum spicant), 

 and, but for the guidance of the Rev. Mr. Maclean, of Aberfeldy, 

 who had previously discovered the station, we should certainly have 

 overlooked it, since it occurred on level ground, close to the road. 

 It has been found in England, Scotland, Wales, and Ireland, where 

 mountains of sufficient elevation have encouraged the search. 

 It is distinguished from the other two species by being persistently 

 only pinnate, that is the pinnae are never divided to the midrib, 



see Fig. 253. Reported finds of the Holly 

 Fern at lower levels are not infrequent, 

 but are invariably found to be young 

 forms of P. aculeatum, by the fact that 

 apart from their less rigidity, the lower- 

 most pinnae are invariably divided. The 

 separation of the species from P. aculea- 

 tum is entirely justified ; it is not merely 

 a mountain form of that, compressed 

 and dwarfed by exposure to hardening 

 influences, and when the spores are sown, 

 the parent form is truly reproduced. Furthermore, plants collected 

 and brought down to lower levels do not respond to milder conditions 

 by larger growth, or the assumption of aculeatum characters, but are 

 difficult to grow, requiring pure air and cooler conditions. We have, 

 however, seen very decent specimens in the open where fairly 

 congenial conditions exist, say in rockeries with stony soil, con- 

 stituting a fair approach to their natural environment. The 

 different pressure of the air is by some considered as constituting 

 a difficulty, but we hardly share this view. We have expressed the 

 opinion that the species is justifiably set apart from P. aculeatum, 

 but may mention that several peculiar cases of the latter species 

 have nvysteriously appeared among sowings of P. lonchilis, to- 





P, lonchitis. 



