AZOLLA IN BRITAIN AND IN EUROPE 209 



from our descriptions, is not accepted as certainly the same. Our 

 R. Marshalli Pocke & Rogers is placed as " var. Marshallii Focke 

 & Rogers " under li. pilocarpus Gremli, together with our very 

 variable var. semiglaher. On this Mr. Marshall's translation 

 (Journ. Bot. 1905, p. 77) of Dr. Focke's remarks in Aschers. & 

 Graebn. (1902-3) may be consulted. Apparently our very re- 

 markable type has not yet been found on the Continent. As to 

 the treatment of B. aciUifrons Ley, reference may be allowed to 

 p. 204 of the same volume of this Journal, where reasons are 

 given for hesitation in accepting the proposed substitution of 

 B. humifasus Wh. & N. for Ley's name. Ley's var. amplifrons 

 (Journ. Bot. 1902, p. 69), though a very strongly marked form, 

 does not seem to be noticed in Buhi Europcei. 



4. Described in Buhi Europai as British, but not as yet 

 detected elsewhere in Europe : — B. Purchasianus Rogers, B. cocj- 

 natus N. E. Brown, B. dasyphyllus Rogers, B. ochrodermis Ley. 

 B. cognatus has a distinct place and brief description in Bubi 

 Europcei, but is held to be very like the Scandinavian B. horridus 

 Hartm. B. dasyphyllus is very briefly and inadequately described 

 by Dr. Focke, and as British only ; but in 1912 I received excel- 

 lent specimens of it collected by Mr. Friderichsen " in woods, 

 Tolne, Denmark," in that year. Apparently otherwise still un- 

 known on the Continent, though exceedingly abundant in Great 

 Britain and frequent in Ireland. 



5. British plants included in London Catalogue, ed. x., but 

 apparently not mentioned in Buhi Europcei : — B. Poioellii Rogers, 

 B. Durotrigum R. P. Murr., B. rotundifolius Bab., B. Buchnalli 

 J. W. White. 



6. British plants recently published, but not included either 

 in London Catalogue, ed. x., or in Bubi Europai : — B. lacustris 

 Rogers, in Journ. Bot. 1907, pp. 9, 10, B. glareosus Rogers & 

 Marshall, in Journ. Bot. 1912, pp. 309, 374. 



AZOLLA IN BRITAIN AND IN EUROPE. 

 By a. S. Marsh, B.A. 



[Reprinted by permission from the Proceedings of the Cam- 

 bridge Philosophical Society, vol. xvii. part 5 (May 5, 1914).] 



In the middle of October 1913 a species of AzoUa was found 

 in Jesus Ditch, Cambridge, by Mr. H. Jeffreys, of St. John's 

 College. Mr. Moss called my attention to the fact, and at his 

 suggestion and with his frequent kind assistance I have identified 

 the species and collected a few notes on the distribution of plants 

 of this genus in Europe generally and the British Isles in 

 particular. 



The Cambridge plant I found to be Azolla filiculoides Lam. It 



was growing among the Lemna, but two or three large patches, 



several metres broad, bore Azolla almost pure, the dull brownish 



colour of the plant as seen in large masses showing up markedly 



Journal of Botany. — Vol. 52. [August, 1914.] r 



