THE ALPINE CERASTIA OF BRITAIN 39 



suggestions on the two other species, which I trust may 

 be of interest. No one can have explored the upper alpine 

 zone of our British montane area without feeling that C. 

 alpinum and C. arcticum (as it has been called) have 

 many intermediate forms. Indeed, from time to time 

 varieties of one or the other species have been made. 

 Conspicuous among these is the var. pubescens^ Syme, which 

 is somewhat laconically described in "Eng. Bot," $rd ed.,vol. ii. 

 85, as "Plant with short hairs," but which receives no 

 mention in Babington's " Manual " or Hooker's " Students' 

 Flora." In 1891 I worked the great mountains which lie to 

 the south of Glen Spean and then saw plants in the Corrie of 

 Aonach Mor which I had no doubt in my own mind were 

 hybrids of C, alpinum with C.vulgatum, = C. triviale X alpinnm, 

 as I recorded it in the "Ann. of Scot. Nat. Hist.," 129, 

 1892. One of our critical botanists thought it was " C. 

 triviale, var. alpestre " ; another, " C. alpinum, L., \zx.pubescens, 

 Syme," and I have no doubt in one sense he was right, for I 

 think it will be found that Syme's plant is made up of the 

 hybrid above named, along with C. vulgatum x nigrescens, and 

 possibly C. alpinum x nigrescens ; and I have the large-flowered 

 alpine form of C. vulgatum so labelled by a good botanist. 

 Recently Dr. C. H. Ostenfeld, to whom I sent my alpine 

 Chickweeds, says : " I have examined your rich material of 

 large-flowered Cerastia from the British Isles with much 

 interest. ... It seems to me that you have in Great Britain 

 only the strongly-haired form of C. alpinum [in Britain 

 named lanatum, but not the true C. lanatum of Lamarck], 

 then C. Edmonstonii [C. nigrescens], and lastly, C. ccsspitosum 

 [C. vulgatum\ with its large-flowered variety alpestre 

 [alpimtmy The Aonach Mor plant referred to, he says, is 

 probably the hybrid I named. To the same parentage I 

 should also refer plants (which Ostenfeld names hybrids) 

 gathered on Ben Lawers and the Cairngorms, in each case C, 

 alpinum, var. pubescens, had been a suggested name. From C. 

 vulgatum, var. alpimim, Hartm., this hybrid may be dis- 

 tinguished by the more shaggy hairs, and usually by the 

 broader and more obtuse leaves, and when in ripe fruit by 

 the seed. But the difficulties of discriminating these large- 

 flowered forms increase when we are investigating localities 



