Why are iris and dahlia roots called bulbs in many catalogs?
It’s a generic term for certain underground structures (not roots) that store food and keep plants alive in a dormant or semi-dormant state from one growing season to another. The underground true bulbs and those that are not true bulbs; some (corms) are mistakenly called bulbs, such as corms, rhizomes, tuberous roots, and tubers. True bulb. A bulb is a thickened, fleshy bud that is formed below the soil surface which carries the plant over from one season to the next. It may have fleshy layers (as in an onion) or thin, dry scales (as in a some lilies). Tulips, daffodils, narcissus, and lilies are bulbs. Corm. A corm is a short, thickened underground stem, usually covered with papery leaves. Corms are organs for food storage and in some plants (e.g., crocus and gladiolus) serve as organs of asexual reproduction. Rhizome. A rhizomes, or rootstock, is a thick, fleshy, creeping underground stem that produces roots and shoots. Buds that form at the joints produce new shoots, so if a rhizom
