A rhizome is a swollen underground stem, from the ends of which shoots, then foliage and flowers emerge, while roots grow on the underside of the rhizome.
Side branches will form each year, typically after flowering has occurred, enabling the plant to spread.
Cannas and zantedeschias are typical rhizomatous plants.
A tuber is a swollen underground root or stem, but it is not the base of the stem, as in the corm.
It is usually fleshy and rounded and may be covered with scaly leaves or with fibrous roots.
Buds usually develop on top of the tuber and produce stems.
Tubers get larger with age and can live for years.
Dahlias, cyclamen and some types of begonia and anemone are tuberous plants.
This last group is of plants that make leaf and root growth when the soil and atmosphere around them is moist, come into bloom and then undergo a period of dormancy during the summer drought.
Such plants come mainly from regions of the world where winters are cool and moist and summers are hot and dry.
In this group of summer and autumn flowering true bulbs, the crinum has a long, tapering neck, while the lilies and smaller tulips are more compact.
Chasmanthe has a wide corm, while freesias are smaller and, for their size, relatively elongated.
Those of gladioli are more rounded.
Cannas produce many fairly large, elongated rhizomes each season, and these can be severed to produce new plants.
Zantedeschia rhizomes can be treated in the same way, although the rhizomes are squatter and more rounded.