Any knob-like outgrowth. A small wart-like swelling on cactus stems, formed by the horizontal division of a rib . A very small tuber. A tuberous root bearing adventitious buds, and functioning like a tuber. A thickened, underground storage organ with stem and root tissues.
Tuberous roots look like tubers, but are actually swollen, nutrient-storing root tissue.
During the growing season, they put out fibrous roots to take up moisture and nutrients. New growth buds, or eyes, form at the base of the stem where it meets the tuberous root. This area is called the crown. To increase tuberous roots, cut off a piece of the root with a section of the crown containing an eye. Daylilies, dahlias, and foxtail lilies have tuberous roots.