Having a central raised area or knob, like an umbo.

A protective sheath or outer layer of certain plant organs.

Top-shaped or inverted cone-like in form.

Shaped like a spinning top; broader at one end and tapering at the other.

Surface layer of soil with grass and roots, often used for lawns or covering ground.

A storage organ in plants, typically underground, formed from stem tissue.

A small, rounded protuberance, often on roots, stems, or seeds.

A tiny wart-like or nodular growth, often functioning as a site for nitrogen fixation in legumes.

Alternative spelling of ‘tubercle’; a small bump or nodule.

Covered with small, wart-like projections or tubercles.