Section A. Structure and Specialized Characters:
II. Roots

A. Root Parts

Root Cap. Parenchymatous, protective apex of root.

Root Hair. Lateral, absorbing outgrowth of the epidermal cell.

Secondary Root. Lateral root with root cap and hairs, derived from the pericycle.

B. Root Types
(Classification based on position and origin)

Adventitious. Arising from organ other than root; usually lateral.

Primary. From radicle of embryo; tip of main axis.

Secondary. From pericycle within the primary or secondary root; lateral.

C. Root Structural Types (Figure 6-1-1)

Aerating or Knee. Vertical or horizontal aboveground roots.

Aerial. Fibrous, adventitious roots, frequently with an adhesive disk; a crampon.

Buttress. Roots with board-like or plank-like growth on upper side, presumably a supporting structure.

Contractile or Pull. Roots capable of shortening, usually drawing the plant or plant part deeper into the soil, usually with a wrinkled surface.

Fascicled. Fleshy or tuberous roots in a cluster.

Fibrous. With fine, threadlike or slender roots.

Fleshy. Succulent roots.

Haustorial. Absorbing roots, within host of some parasitic species.

Moniliform. Elongate roots with regularly arranged swollen areas.

Pneumatophorous. With spongy, aerating roots, usually found in marsh plants.

Prop or Stilt. Adventitious, supporting roots usually arising at lower nodes.

Tap. Persistent, well-developed primary root.

Tuberous. Fleshy roots resembling stem tubers.