FERN TRIBE 113 
as are also those of the lower branches, and the upper part of the frond. A 
distinct winding mid-vein may be seen in each pinnule or lobe, whence issue 
lateral veins, cither simple or slightly branched, near the termination of 
which, towards the margin, are placed the round clusters of fructification, 
which in the autumn run into a crowded mass, and form a marginal series. 
The underground stem of this fern is dark-brown and creeping, and its 
fibrous roots tough. Freshly-gathered specimens exhibit a degree of downi- 
ness on the frond. It isa rare fern, growing among the loose stones of the 
limestone regions. It does not thrive so well as several of the species in 
gardens near towns, but sometimes in country gardens it grows well, 
requiring lime to be mixed with the soil. It seldom grows very abundantly, 
though it is plentiful on the rocks of Buxton, about Matlock Baths, and the 
Cheddar cliffs, for it seems never to grow wild except in limestone districts. 
Some authors term it Polypédium roberiiénum, and under this name it is now 
usually regarded as a sub-species of P. dryopteris. 
5. Alpine Polypody (P. alpéstre).—Fronds lanceolate, twice pinnate ; 
pinnules linear-lanceolate, pinnatifid, with blunt sharply-serrated lobes. 
This fern had long been known as a native of Switzerland, as well as of 
several countries at the north and in the middle of Europe, but it was first 
discovered in Britain in 1841, by Mr. Watson, on the mountains near Dal- 
whinnie, and at Great Corrie of Ben Alder, Inverness-shire. It was not, 
however, until 1844, when this botanist again saw this fern in Canlochen 
Glen in Forfarshire, that its claim as a British plant was fully recognised by 
botanists, and it was proved to be the fern known by Continental writers as 
Aspidium alpéstre, or Aspidium rheticum. It is so like the Lady Fern (Athyrium 
filix-femina) in its outline and general appearance, that it has doubtless often 
been overlooked, and believed to be an alpine variety of that plant ; for it 
has since been found to be a not infrequent fern on mountains from Suther- 
land to Argyll and Perth. Some writers consider that this fern has at an 
early period of its growth an indusium over its circular clusters, and this may 
have induced the Continental botanists to class it with Aspidiwn. Mr. 
Newman constitutes it a new genus, and calls it Pseudathyrium ; while avery 
elegant form of the fern, termed by him P. flézile, has proved to be but a 
variety of this plant. 
This Alpine Polypody is a very graceful fern, the fronds growing in 
- circular clumps from the crown of a creeping rhizome, and being a foot or a 
foot and a half high. These fronds are lanceolate, twice-pinnate, narrowed 
to the base, as much so as at the upper part of the frond, and the leafy 
portion extends almost to the base of the scaly stalk. The pinne are 
lanceolate and tapering ; the pinnules lanceolate, acute, and deeply pinnatifid, 
with serrated segments. The clusters of fructification are small and circular, 
and are generally placed on the depressed spots between the lobes of the 
pinnule, and thus form two distinct lines on each side of the mid-rib, and 
parallel to it ; but sometimes they are more numerous, and in maturity form 
one mass. In the var. flexile the stipes is very short, the pinnz are short 
with a downward rather than an upward tendency, and the pinnules are not 
crowded as in the type. 
Iv.—15 
