THE ROOT. 35 
matter, intended to nourish the herb of the ensuing season, 
and accordingly are found only in perennial plants. Potato 
(Solanum tuberosa), Orchis, Common Dropwort (Spirea fili- 
pendula), are examples. 
100. Those tubercles which have eyes may be considered 
thick, short, fleshy, subterraneous stems; the eyes on their 
surface being analogous to the buds on the stem. The 
Potato is propagated by meanis of these fleshy tubercles; and 
only those parts of the mass which have eyes (concealed 
buds) have the power of producing new plants. 
101. In the Orchis, which has two tubercles, and the 
stem of which dies annually, one of the tubercles affords 
nourishment to the annual stem, shrinks, and disappears. 
The other contains nutritious matter for the growth of the 
stem of the succeeding season, and disappears in its turn ; 
and gradually a third is formed to serve the same office in 
the ensuing season: and so on for many successive years. 
102. When there are two tubercles, the root is called twin 
or didymate: Military Orchis. When the tuber is divided 
deeply by fissures extending to the middle of its substance, 
presenting an appearance like the hand and fingers, it is 
called palmate : Spotted palmate Orchis (Orchis maculata). 
When the tuber is divided still more deeply, it is called di- 
gitate: White Orchis (Satyrium albidium, Habenaria albida 
of Dr. Hooker.) 
103. Butsous Root. This root is of two kinds; tuni- 
cate or coated, consisting of concentric hollow spheres, as in 
Onion (Allium), Squill (Scilla), (See Fig. 7. next page); and 
scaly (squamosus) with scales covering each other like the 
slates on a house-top, as in the Lily (Lilium). What is us- 
ually termed the solid bulb, as that of Buttercup (Ranunculus 
__ bulbosus), Crocus, Meadow saffron (Colchicum), is not form- 
ed of compressed or adherent scales, but is simply a glo- 
bular fleshy subterraneous stem. It has been termed t= 
_ Cormus. 
