Adventitious roots are modified for storage and many other functions like additional support, nutrition and respiration. They are also form tubers. They may be tuberous, fasciculated, moniliform, nodulose and annulated.
a) Tuberous roots: they are swollen, irregularly shaped tubers which arise single from each node.
Example: Sweet potato (Ipomoea batatus)
b) Fasciculated: When storage roots occur in clusters from the base of the stem they are called fasciculated roots.
Example: Asparagus, Tapioca and Dahlia
c) Moniliform (Beaded roots): A moniliform root is alternatively swollen and constricted giving a beaded appearance.
Example:Bitter gourd (Momordica charantia) and Portulaca. 
d) Nodulose roots: When a slender root is swollen abruptly at the apex it is said to be nodulose.
d) Nodulose roots: When a slender root is swollen abruptly at the apex it is said to be nodulose.
Example: Mango ginger (Curcuma amada)
e) Annulated: When the root appears to be formed by numerous discs placed one above the other it is said to be annulated.
Example:Ipecac (Psychotria)
See also: Example of Tap root tubers