ROOTS. 65 
tumors, situated at the base among the fibres. Ex. Orchis. 
This root must be distinguished from the twber, which, like the 
potatoe, uniformly bears buds, and is now classed among stems. 
a. A palmate (hand-shaped) root is a variety of the tuberous, 
where the knob is separated below into short, thickened pro- 
cesses, as in some species of the Orchis. 
b. A granulated root consists of many small tubercular knobs, 
connected by te as seen in the common wood sorrel. Some 
writers call thi iety moniliform (monile, a necklace). 
FIG. 21.— Forms of the root;—1, Raphanus; 2, Brassica rapa; 3, Scabiosa; 4, Poa; 
5, Peonia; 6, Dahlia. 
148. All the above forms of fleshy roots appear to be reser- 
voirs where the superabundant nutriment secreted by the plant, 
is accumulated and kept in store for the following year, or for 
the time of flowering. 
a. To the varieties already mentioned, we may add several others, which are 
remarkably distinguished by their not being fixed in the soil. 
149. The floating root is peculiar to plants which float loosely 
upon the surface of the water. Ex. Lemna, Callitriche. The 
latter, called water starwort, floats upon the surface only until 
flowering, after which it sinks to the bottom, fixes its roots in 
the mud, and there ripens its seeds. 
\150. Aerial roots are those which, instead of originating from 
portions of the plant beneath the surface of the ground, are pro- 
duced from some portion in the open air. Of these roots, seve- 
ral varieties are remarkable. 1st, Those which are sent forth 
