J. SAUNDERS witches' BROOMS. 71 



apparently coincident. In July the leaves on the broom were 

 seen to be in a damaged condition. Most of them appeared to 

 have been partly eaten by lai'vae, and on many of them were 

 brown patches suggesting the presence of a parasitic fungus. In 

 September all the leaves of the broom had withered and fallen, 

 whilst those of the healthy part of the tree were assiuning their 

 normal autumn tints. Many of the latter were marked with 

 brown spots, on which were numerous asci containing elongate 

 spores, probably the fruiting-stage of Taphrina TJlmi, Johan. 

 (Exoasc'us JJlmi, Fuckel). In ' Bot. Zeitung,' 1895, this species 

 is described as occurring on leaves of elm from Jvme to October. 



In Stockwood Park, Luton, there are other examples on 

 common elm. On one of these is a broom very similar in 

 appearance to that at Limbm-y. It grows on a tree not less in 

 age than one hundi-ed years, and the broom is much older than 

 that referred to above. Another elm, also an aged one, which is 

 probal)ly the largest tree in Stockwood Park, is infested with 

 these parasitic growths. Some of them are living and others 

 dead. Two of the latter now appear as large excrescences on 

 primary branches, and must have taken many years to produce. 

 Another large broom is in a moribund condition, and bears only 

 a few living twigs. These excrescences mark the places where the 

 parasitic fungus has effected the maximimi of injury to the tree. 



On Brewer's Hill, Wheathampstead, there is a fine example 

 on common elm, which was first observed by the writer on 

 8th May, 1904. It is a conspicuous object, and can be seen 

 from the distance of a mile when approached from Harpenden. 

 It occupies the highest part of a tree which has an altitude of 

 not less than fifty feet. The broom is about three feet in height 

 and five in width. By the aid of a telescope it was seen that 

 the foliage was crumpled, as well as smaller and more crowded 

 than on the normal part of the tree. 



Dr. W. Gr. Smith, in a letter dated 14th January, 1904, writes 

 to me : " Ee Ulrmis, the only Taphrina on it at present known is 

 a leaf-form which does not produce witches' brooms. I recently 

 saw the manuscript of an investigation which dealt with gnarling, 

 and these growths on elm were traced to this cause. A few years 

 ago the Botanical Department at Manchester University secured 

 a splendid specimen of elm broom. They consulted with me 

 about it, but in spite of careful investigation they could find no 

 Exoasciis. From my own examination I am inclined to put the 

 elm brooms down to abnormal growth, without reference to fungi 

 or insects." 



The evidence of the elms in Stockwood Park is strongly 

 suggestive of the presence of a parasitic fungus, which is probably 

 the agent in the formation of the brooms that they produce. 

 The balance of evidence of the Limbury specimen is in favoTir of 

 gnarling as the proximate cause. 



Wych Elm (Ulmus montana, Sm.).- — A small broom is present 

 on a large wych elm at the Bedford Eoad end of Villa Road, 



