On the Nature and Development of the Corky 
Excrescences on Stems of Zanthoxylum. 
BY 
C. A. BARBER, B.A., 
Superintendent , Agricultural Department , Leeward Islands , 
Late Scholar of Christ's College , and De?nonstrator of Botany in the 
University of Cambridge. 
With Plates VII and VIII. 
ONICAL excrescences on the trunks of trees, frequently 
of striking size and marvellous symmetry, have always 
attracted the attention of settlers and explorers in foreign 
lands ; and these objects are consequently by no means 
uncommon in our museums. 
Perhaps the name most frequently met with in collections 
is that of Zanthoxylum Clava-Herculis. The stems of this 
species vary considerably in their appearance, according to 
the regularity and size of the cones. Sometimes the 
specimens are covered by a cracked, irregular bark, but in 
the majority of cases the surface of the stem is covered by 
isolated limpet-shaped protrusions (Figs, i, 2). 
The excrescences are, it is true, of little value economically, 
and the trunks bearing them are usually preserved merely as 
curiosities. Yet the ‘ Ambeck ’ or thorny cinnamon of the 
Colonial Exhibition of 1886 consists of these bodies, while 
the cones on Araliaceous stems are said to be sold as a 
cosmetic in the bazaars of Burmah. Many of the smaller 
branches, especially of Zanthoxylum Clava-Herculis , are used 
[Annals of Botany, Vol. VI. No. XXII. July 1892.] 
M 
