On two new instances of Spinous Roots. 
BY 
D. H. SCOTT, M.A., Ph.D., F.R.S. 
Honorary Keeper of the Jodrell Laboratory, Royal Gardens , Kew. 
With Plates XV and XVI. 
OMPARATIVELY few instances of spinous roots 
V_y appear to have been recorded hitherto. Among the 
better known cases of the kind are certain Palms, such as 
the species of Iriartea and Acanthorhiza , in which the rootlets 
of the aerial roots are modified to form spines ; and the 
Leguminous genus Derris , in which the adventitious roots 
themselves are said to become spinous, and to help in attach- 
ing the climbing stem to its support. 
The object of the present brief communication is to place 
on record two remarkable, and as I believe novel, instances 
of spinous roots, which, curiously enough, have almost simul- 
taneously come under observation at Kew, within the last 
few months. 
Both the plants in question are Monocotyledons, but they 
belong to distinct Natural Orders, and are totally different 
in habit, the one being a Dioscorea and the other a Moraea. 
i. Dioscorea prehensilis, Benth. 
The Dioscorea was raised from seed collected by Mr. Scott- 
Elliot in Sierra Leone, and presented to Kew in January, 
1892. The plant flowered in September, 1894, and was then 
determined as the Dioscorea prehensilis of Bentham. The 
[Annals of Botany, Vol. XI. No. XLII. June, 1897.] 
