I4 2 
European Ferns. 
auriclcd. The fructification is as usual on the back of the frond, 
and is confined for the most part to its upper half ; the sori 
are round, covered with a membranous indusium situated upon the 
venules, nearer to their base than their apex : they are often very 
numerous, and sometimes become confluent. The pinnules of the 
fronds of young plants are much broader in proportion to their 
length. The beauty of the vernation of P. aculeatum has attracted 
the notice of most authors. “ It arises from the rhizome, closely 
curled inwards ; but when it is more expanded, it droops back- 
ward, while the extremity still retains its tendency to curl inwards, 
thus forming a double curve, and having a most graceful ap- 
pearance.”* 
The geographical range of P. aculeatum is as wide as that 
of any European fern, as may be gathered 
from a glance at the table of distribution, 
where it is noted as occurring in seventeen 
out of the eighteen divisions, being absent 
only from the eastern peninsula and archipelago 
of Asia, including the Philippine Islands. It 
is found almost throughout Europe, although 
not always very abundantly, being however 
rare if not absent in the extreme north. It 
will probably be found to occur in all of the 
English, and most likely in all of the Scotch 
counties, although there are at present a few 
gaps in the list : the Scotch plant is for the 
most part the form lobatum. In Ireland, 
although it occurs in nearly all the districts 
into which the flora of that country has been 
divided, it is local and not common. If we 
go farther afield, beyond the European 
boundary, we shall find the distribution of 
P. aculeatum somewhat difficult to ascertain, 
as it is so often united by authors with the 
next species, P. angulare ; but it seems to be 
very generally met with. A very exhaustive 
summary of the distribution of the species 
considered in a large sense, and including 
under the same head a large number of forms 
besides P. augulare , will be found in the 
“Species Filicum”;f here it is traced through- 
out the world. Sir W. J. Plooker remarks 
that he has seen no well-pronounced form of 
it from the West Indian Islands, but is inclined 
POI.YSTICHUM ACULEATUM. 
* Deakin’s “Florigraphia Britannica,” iv. 95. 
f “Species Filicum,” vol. iv., pp. 18 — 22. 
