328 Scott . — On tivo new instances of Spinous Roots. 
peculiarity of the roots was first noticed in February of the 
present year. The plant was at that time at rest, the leafy 
stems having withered. When dug up, it was found to have 
formed an irregular, lobed tuber about a foot long, which was 
enclosed in a sort of cage of hard, interlacing, spine-bearing 
roots, springing from the upper part of the tuber, the whole 
mass being about two feet in diameter (see Plate XV). At 
that time the normal nutritive roots, bearing ordinary rootlets, 
appeared to be produced only from the base of the stem, 
immediately above its attachment to the tuber. 
It is important to notice that the whole system of spinous 
roots was produced entirely underground, so that their 
existence was not revealed until the soil was removed. That 
they form a most efficient means of protection to the parts 
which they enclose is evident from the photograph, and is 
still more vividly realized by any one who has attempted 
to handle the rigid and bristling mass. We may reasonably 
suppose that the thorny hedge of roots serves to guard the 
tuber — the great food-store of the plant — from the attacks 
of burrowing or digging animals. 
The spinous roots attain a diameter of about a quarter of 
an inch. They have an irregular curved course, usually 
starting from the tuber in an upward direction, and then 
bending down. In the mature condition they are very hard 
and woody, and consist entirely of the vascular cylinder or 
stele, the whole cortex beyond the endodermis having 
withered, and only hanging on the roots in shreds. The 
spines, which are inserted at irregular intervals, averaging an 
inch or less, reach a length of about three-quarters of an inch. 
They are sometimes solitary, in other cases two or three are 
inserted together at the same level, and on the same side 
of the root. It occasionally happens that two adjacent spines 
are coherent, having a common base, which may much exceed 
the free points in length. The spines themselves are ex- 
ceedingly hard, and usually very sharp. 
The study of the anatomy shows plainly that the spine- 
bearing organs are actually roots, in which the vascular 
