NOTE ON LEUCOBRYUM 319 



habitat may l)e of interest. Hundreds of bosses, or cushions, of 

 Leucohrywn are to seen growing under both fir-trees and beech- 

 trees, but chiefly under fir-trees, in tlie woods in question ; and, on 

 examination, a certain number of these cushions will be found to 

 have no attachment to the ground. They lie loosely on the 

 brown litter of pine-needles or dry leaves, and their upper and 

 under sides show precisely the same surface of growing moss. 

 Sometimes one side of the double disc is convex and the other 

 flat ; sometimes both sides are slightly convex. The discs vary 

 from about H in. to 4 in. in diameter, and the largest are about 

 If in. thick in the centre. 



In a paper contributed to The Bryologist in November, 1907, 

 Mr. Burrell attributes the unattached state of " double convex 

 discs " of L. glaucum found at different times in Norfolk and 

 Buckinghamshire to " accidental and repeated disturbance." He 

 refers to the abnormal vitality and persistent growth of the moss, 

 and suggests that when a cushion is detached from the ground, 

 and left with the base turned upwards, it continues to grow in 

 that position ; he also points out that Leucohrijum holds in its 

 ' cells sufficient water to " render unattached tufts self-sustaining " 

 for a considerable period. " The tread of w^oodmen and sports- 

 men and the removal of timber play their part," this writer says, 

 in continually shifting the loosened discs ; but it is probable, he 

 adds, that " in well-stocked game-preserves " they are much more 

 frequently turned over and moved by birds. The constant dis- 

 turbance results in " alternating growth taking place in two 

 different directions." 



It seems impossible to suggest a better explanation of the 

 origin of the discs than the one put forward by Mr. Burrell. At 

 the same time, it is difficult to understand why, if the causes of 

 their formation are so simple, and the conditions necessary to 

 that formation are conditions which prevail in vast areas of wood- 

 land, the double discs are not more common. For about twelve 

 weeks this summer I walked almost daily in the woods near 

 Fawley, and saw in them immense quantities of L. glaucum ; but 

 only in one large stretch of woods did I find unattached cushions. 

 I afterwards learnt that they are so well known in these particular 

 woods that they have received the popular local name of " Fawley 

 buns." 



I may mention that I never discovered an unattached double 

 disc with one side looking greener and more vigorous than the 

 other ; both sides always appeared to be equally active, if one 

 may so express it. I may also mention that where one surface 

 was convex and the other fiat, the growth on the flat side some- 

 times appeared to radiate from a centre. It is perhaps worthy 

 of note that the tufts of moss which I saw that had obviously 

 been recently loosened from the ground seemed to have a ten- 

 dency to fall to pieces quickly ; I do not think I ever noticed a tuft 

 lying base upwards and looking fresh and healthy ; possibly tlie 

 extreme dryness of the weather would account for this. 



