316 TRANSACTIONS AND PEOCEEDINGS OF THE [Sess. lxiv. 



incline outwards and upwards, and not strictly horizontal 

 as ordinary lateral branches of Picca do. The dorsiven- 

 tiality, so marked owing to the habit of the branches and 

 leaf arrangements of ordinary shoots, disappears in the 

 broom shoots, in so far as the leaves aie concerned, but 

 is retained to some extent in the branching. The leaves 

 show a radial disposition around the free apices of the 

 ascending shoots, while the lateral branches arise generally 

 in two rows right and left, and so crowded, as already 

 mentioned, that they mutually compress each other. 



The leaves show structural variations from the normal^ 

 e.g. in external shape, anatomy of the stomata, disposition 

 of the stomatal bands, arrangement of the lignified tissues, 

 as well as variations and peculiarities in the degree of 

 lignification. 



My two other brooms occur on an ash {Fraxinus 

 exccisio/', L.) and a thorn {Cratcegus Oxyacantha, L.) respec- 

 tively. The former I came across accidentally some years 

 ago while botanising in the west of Fife ; my acquaintance 

 with the latter I owe to the kindness of Mr. Duff, forester 

 to the Earl of Elgin, on whose estate in the west of Fife 

 it occurs. 



So far as I can discover, these are the first recorded 

 cases of brooms on either of these trees. On the privet 

 and the lilac, meml:)ers like the ash of the Oleaccie, 

 brooms induced by the attacks of Gallmites are well 

 known ; while on allies of the thorn, brooms are more 

 familiar still, notably those on the cherry, caused by the 

 agency of exoascous fungi. 



The ash in question here grows by the side of the 

 public road, in a field of somewhat stiff clay soil. At 

 breast -height it has a girth of 45 inches, and it 

 branches at about seven feet from the ground. The 

 first seven branches, all on the south side of the tree, 

 are mere dead stumps ; the eighth branch on the same 

 side, 11 feet from the ground, bears the broom. At 

 this point the trunk is 29 inches in circumference. A 

 little higher up, but on the opposite side, a large branch 

 arises which forms the greater part of the north side 

 of the tree, and which apparently is also infected, as it 

 .show.s broom characters, tliongli not so ])ronounced as in 



