POLYPODIUM. 
121 
is dull in itself. Mr. Moore regards the two as entirely 
distinct species, and in proof thereof cites a peculiar 
habit in the infant frond, each pinna being rolled in se- 
parately, instead of all pertaining to each of the three 
branches being packed in one ball, as in the case of P . 
Dryopteris. We would venture to add, from our own 
observation, that the Polypodium Robertianum grows, 
both in its native woods and under cultivation, in a more 
dense and compact style than in P. Dryopteris , forming 
clusters of fronds closely packed together, like the Pale 
Mountain Polypody, rather than fanciful lines and light 
groups like the related species. 
This fern is never found except on a limestone soil. 
It has been frequently found on Ingleborough, and we 
know it well as an inhabitant of the Yorkshire dales and 
Somersetshire combes. 
It succeeds well in the fernery, requiring a compost 
like its fellows, and a free supply of water during the 
growing season. 
6. Polypodium alpestre* Hoppe. Alpine Polypody. 
( Athyrium Rhceticum . Roth ; Poly podium, flexile, Moore.) 
Caudex oblique. Stem short and scaly. Fronds lanceolate. 
Sori round, marginal. 
The caudex of this fern is horizontal or oblique, bear- 
ing a crown-shaped tuft of fronds at the point of each 
branch. The stems are enlarged at the base, and very 
short, because of early commencement of the leafy por- 
tion of the frond ; they are covered with large brown 
scales. The frond is lanceolate and bipinnate, the leaf- 
lets are oblong and unstalked. 
This fern is very distinct from all other members of 
