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PLAGIOTHECIUM MULLERIANUM Schimp. IN BRITAIN. 



By H. N. Dixon, M.A., F.L.S. 



(Plate 387.) 



In July, 1897, I gathered a Plaglothecium on the side of Craig 

 Chailleach, near Killin, Perthshire, which had somewhat the ap- 

 pearance of P. pulchellum var. nitididum (Wahl.) Husn., but which 

 I was unable to determine without closer examination than could 

 be given at the time. 



Shortly after returning home, and before I had found the 

 opportunity of further studying this plant, I received from Mr. 

 James Murray two fragments of a Plagiothecium, both evidently 

 belonging to one and the same species, one labelled ^^ Flag. 

 Mullerianum, in rupium fissuris, Ben Wyvis, Aug. 1867, N. Suther- 

 land & A. McKinlay"; the other unnamed, from Ben Narnain, 

 Arrochar, 18 July, 1896, gathered by Mr. Murray himself. The 

 general appearance of these plants was that of P. Borrerianum 

 Spr., being fully as robust as that species in its ordinary form, but 

 with a somewhat more rigid habit, and even more highly glossy and 

 shining, the leaves complanate, of almost exactly the same form as 

 in P. Borrerianum, somewhat abruptly ending in a moderately long, 

 fine, perfectly entire acumen. On consulting the description of 

 P. Mullerianum Schp. in the 2nd ed. of the Synopsis, I saw at 

 once that it would not agree ; such characters, for instance, as 

 " minutulum, PL imlchello vix majus," ''Folia .... elongato- 

 lanceolata sensim in apiculum longum sub-piliformem attenuata," 

 being quite inconsistent with the plants before me. Besides which, 

 Schimper's note to the effect that it " differs from P. pulchellwu 

 in the longer, highly glossy leaves, complanately spreading, the 

 dioicous inflorescence, the incurved, cylindraceous capsule and 

 rostrate lid/' certainly leads one to conclude that it practically 

 only differs from the var. nitididum of that species in the dioicous, 

 not autoicous inflorescence. 



I therefore referred the plants with some hesitation to P. Bor- 

 rerianum. Mr. Murray concurred with my view as regards P. 

 Mullerianum, but pointed out a very marked character in the 

 large cortical cells of the stem, clearly separating the plants in 

 question from P. Borrerianum, in which the cortical cells are 

 narrow and obscure. The matter was left in this unsatisfactory 

 position until on examining my plant from Killin, referred to 

 above, I at once perceived that I had there the same species as 

 the two plants sub judice. What was most marked in the Killin 

 plant was the great variety in the size of the stems and leaves, 

 varying from shoots as robust as in P. Borrerianum to the most 

 slender, almost filiform flagellae. The resemblance here to the 

 P. Mullerianum of Schimper's Synopsis became at once apparent, 

 and on comparison of my plant with authentic specimens in the 



Journal of Botany. — Vol. 3Q. [July, 1898.] s 



