170 
European Ferns. 
only occasional, or even rare, and they appear never to be seen in company with the more 
perfect sori, but only where the spore-cases are much fewer in number than usual. Now 
they have the appearance of lacerated membranaceo-filamentous expansions of those points 
of the veins which form the receptacles, and appear to arise from some abnormal condition, 
perhaps inherent, which limits the power of producing spore-cases to the side or base of the 
receptacle, while on the upper side its cells are directly prolonged into the indusioid membrane. 
In no case have we seen what could be considered as a perfect and fully developed indusium.” 
The stem or caudex of Polypodium alpestre is short and stout, with a broad scaly crown, 
the fronds being arranged in a shuttle-cock-like fashion. These are from a foot to three feet 
or more in height, the stipes being about a sixth of the whole frond ; this is clothed rather sparingly 
with long light-brown scales. The habit of the fronds is somewhat stiff, upright or ascending ; 
they are lanceolate and taper both to the base and to the apex, measuring about six inches or so 
across in their widest part. The pinnae, of which there are from twenty to thirty pairs upon 
the average frond, are ascending and narrow, with ovate oblong acute pinnules, which are 
connected at the base by a narrow wing ; they are deeply cut or lobed. The sori are placed 
on the back of the lowermost venules, and appear as though placed in a notch between 
two lobes of the pinnules ; they are confined to the upper half or two-thirds of the frond. 
The distribution of Polypodium alpestre is by no means wide. In Britain it is mainly 
confined to the east Highlands of Scotland, where it is abundant, often growing with the Lady 
Fern ; and it occurs also sparingly in Inverness-shire and Sutherlandshire. It is apparently 
much relished by sheep, and collectors have said that it is difficult to obtain specimens which 
have not been cropped by these animals. It has not been found in Ireland, and its European 
distribution is limited. It is most frequently met with in the north, being abundant in 
Norway, Sweden, and Lapland ; it is found in the Carpathian Mountains, the Black Forest, 
and in the Pyrenees, but is rare in the south ; it is recorded from the Caucasus, and from 
Lazistan in Asia Minor. In the New World it is found in Sitka, California, and Oregon. 
POLYPODIUM FLEXILE, Moore. 
This is a plant nearly allied to the preceding, and probably only a well-marked variety 
of it, although it is kej:>t distinct by Newman. It is a more slender and delicate plant than 
P. alpestre ; in general outline it is much narrower, the pinnae being shorter, and the stipes 
very short or even absent ; the sori are borne upon the lower portion of the fronds. Dr. 
F. B. White has published a paper upon these two plants, in which, after contrasting a 
series of specimens of each, he considers the narrow base of the pinnules, the somewhat 
narrower frond, and the general habit of the plant as the only characters by which P. flexile 
can be separated from P. alpestre. This being practically all that can be found in the way 
of specific character, it is rather strange to find Dr. White advocating the maintenance of the 
two as distinct species. P. flexile is even more restricted in geographical range than P. alpestre. 
Its best known locality is Glen Proven, Forfarshire, and it is said to have been found in Suther- 
landshire ; Milde records it as occurring in Lithuania. 
The two plants are not difficult to grow. The first will do well in an open border in 
bog-earth; in a greenhouse it flourishes in similar soil, in a large pot, plenty of water being 
supplied, which must not be suffered to stagnate. P. flexile makes a very pretty pot-plant 
in a cool greenhouse, requiring similar treatment to that advised for A*, alpestre. 
