May, 1923. The Irish Naturalist. as^ 



POROTRICHUM ANGUSTIFOLIUM IN IRELAND. 



BY H. N. DIXON, F.L.S. 



Porotrichiun angustifolium Dixon {Thamnium angusti- 

 folium Holt) is one of the few mosses with a genuine claim 

 to be endemic in the British Isles. Its characters are 

 marked and well defined ; while the fact that it grows 

 intermixed with P. alopecurum, each keeping its own 

 characters, precludes any idea of its being a form due to 

 local conditions. And more than that, it has hitherto 

 been known from one sole station in Derbyshire, where it 

 is indeed confined to a single and rather limited rock- 

 surface. 



It is therefore of special interest that it appears to be 

 also an Irish plant. Two records have come under my 

 notice, which must be dealt with separately. 



1. It is recorded by the late Canon Lett from Co. Kerry 

 in his " Census Report on the Mosses of Ireland " (Proc. 

 Roy. Irish Acad, xxxii., 162 (1915). The record reads 

 " 2 Derrycunnihy 1906 — H. W. L." 



Unhappily the record is incorrect. I have been allowed, 

 by the courtesy of the Acting Director, to examine the 

 specimen of the original plant collected by Lett, in the 

 National Museum at Dublin. There is only one specimen. 

 It is a form of P. alopecurum, slightly different from the 

 normal forms ; one peculiar to rocky sides and boulders 

 of mountain streams ; growing in similar situations to, 

 and not unlike Eurhynchium myosuroides var. riviilare Holt. 



2. The second record rests on a much firmer basis, the 

 information for which I owe to Mr. H. C. Broome. Mr. 

 Broome has in his possession the herbarium of the late 

 Mr. Levi Tetlow, an ardent Lancashire naturalist, and a 

 keen moss collector. Among the mosses in the collection 

 are two from Ireland, both labelled in Tetlow's hand as 

 being collected by Jas. Shepley (of Oldham) in Ireland, in 

 1898. One is labelled " Dicranum undulatiim, Glenariff, 

 Ireland, 1898 c[olL] J. Shepley." This, however, is not 

 D. undulatum, but a very rugose-leaved form of D. Bonjeani 

 referable probably to var. rugifolium Boswell. 



A 



