bulb vegetables [1]
The main edible part of these vegetables is their bulb, the underground structure where the plant’s nutrient reserves are stored.
scallion 
Its bulb is less developed than that of the green onion; the white part is used like the onion and the green is used to season a variety of dishes.
water chestnut 
The aquatic bulb of a Chinese plant; its white crunchy flesh is an important ingredient in many Asian dishes.
green onion 
Mild onion picked before fully ripe; it is usually sold with the stem, in bunches. It is often eaten raw in salads or cooked in sautéed dishes.
chive 
Smallest member of the onion family; its stem is used primarily to season various hot and cold dishes.
leek 
The white part is the most popular, but the green part adds flavor to puréed soups and stews; it is often combined with potatoes in a cold soup called vichyssoise.