Any plant described as ‘bulbous’ will normally have a swollen
root or stem – or even leaves – underground. (Some orchids and
other plants have swollen stems – above ground. These are not
normally referred to as being bulbous!
The purpose of the bulbous part of the plant is to store food for the plant parts that live above ground. It may well be that the plant dies down for a rest at some part of the year.
The ‘bulbous’ part of the plant will store the food needed for the plant to restart growth when it is ready.
A good show of Tuberous Begonias. The tubers can be kept overwinter and re-started in spring. - Tender
A display of healthy Tulip Bulbs to be found at garden centres in September-October. - Hardy
Cyclamen coum Hybrids - Grow from a corm that is just below, or at the soil surface. It is left in position in the garden. - Hardy
Flag Iris - Grows from rhizomes which sit on the surface of the soil. - Hardy