SCIENCE-GOSSIP. 



2«I 



ATROPHY OF TREE-BRANCHES. 



By John T. Carrington. 





**^%;:d. 



HpHE drawing of a Pinus sylvestris in the centre 

 of this page is given to represent a remark- 

 able mass of twig growth on one of the lower 

 branches. This Scotch fir-tree is growing on the 

 estate of Mr. W. H. Smyth, at Elkington Hall, 

 near Louth, Lincolnshire. In size the mass is 

 about six feet long by about five feet wide, and 

 five feet thick from top to bottom. It is ex- 

 tremely dense, the twigs being quite matted 

 together. Unfortunately, the lower portion of it is 

 dead, as shown by the bare branches in the drawing, 

 the mass having some time ago been set on fire. 

 Still, this abnormal growth is very remarkable. 

 We are favoured with these 

 particulars by Mr. H. Wallis 

 Kew, who knows the tree 

 well, and has lent us a sketch, 

 from which Miss Hensman 

 has kindly made the pretty 

 drawing we have reproduced. 

 At one time the owner of 

 this tree contemplated its 

 removal to a site near his 

 house, but the idea was 

 abandoned on account of the 

 possibly fatal results to the 

 tree and the great cost of 

 the undertaking. 



These abnormal bunch-like 

 growths are by no means un- 

 common, and are familiar to 

 most of us, especially on some 

 birch-trees. They are caused 

 by a condition of atrophy in 

 the growth of the branch. Dr. 

 Maxwell Masters refers only 

 slightly to atrophy of tree- 

 branches in his "Vegetable 

 Tetrology," and there does 

 not seem to have been much 

 written about it by other 



authorities in more than a general way. It is a 

 subject which will bear some discussion in these 

 columns, and exceptional cases might well be 

 recorded. 



Dr. Masters divides atrophy in vegetable growth 

 into two sections, viz., abortion and degeneration. 

 Abortion includes in this sense the arrest of 

 development of organs, occurring at an early stage, 

 the effect being to leave them much smaller and 

 more rudimentary in condition than in the normal 

 type, but materially unaltered. By degeneration 

 is meant that the development is not entirely 

 checked, but perverted ; so that not only are the 



January, 1896.— No. 23, Vol. II. M 



Abnormal Pinus Sylvestris 



parts affected lessened, but the form is altered. 

 Under this last section these tree-tufts are to be 

 classed, and as I have already said, the commonly- 

 seen tufts of small branches in birch-trees are 

 excellent examples of degenerated development, or 

 arrested growth. 



From some cause, whether naturally, or in 

 consequence of injury does not appear to be clearly 

 known, the branch suddenly ceases to increase in 

 length. Growth, however, continues at the end of 

 the branch by forming a small bulbous knob, from 

 which are developed a profusion of little twigs. 

 These sprout out, apparently in any direction, 

 frequently exactly opposite to 

 that of the natural extension 

 of the branch. The result 

 is the formation of the birds'- 

 nest-like masses so often seen 

 among the branches of birch- 

 trees. Several other species 

 of trees are liable to these 

 abnormities, such as horn- 

 beam and thorn. In the fir 

 forests of central Europe, 

 tufts may occasionally be 

 seen on conifers, which are 

 said to be caused by attacks 

 of a small fungus, which 

 places the branch in one of 

 the categories of atrophy. 



It seems probable that the 

 abnormal tufty growth of 

 branches may be caused by 

 injury when young, for there 

 is on record a case of a grafted 

 ash, that produced a large 

 swelling below the graft, from 

 which proceeded more than 

 a thousand densely-packed 

 and interlacing twigs. We 

 have all seen how readily 

 little twigs grow on elm-trees when the lower 

 branches are cut off in agricultural districts, and 

 again in the case of pollard-trees of any kind. The 

 injury which causes these twig masses may not 

 necessarily be the result of man's action, nor 

 indeed of any animal. Frost might be a possible 

 solution of the origin. It is doubtful whether 

 sufficient importance is credited to the results of 

 injury of young plant-growth by spring frosts, 

 when considering the modifications and devia- 

 tions from the type so frequently found among 

 vegetation. We shall be glad to have this subject 

 discussed in our pages. 



