Plants develop spreading lateral roots that can extend several meters outwards in all directions in the upper soil layers and deep taproots to depths of 4 m or more. Roots associate with nitrogen-fixing bacteria. Plants cut down to the ground produce new shoots from dormant stem buds on the crown at or just below soil level, but not from roots. Flower heads axillary. Flowers small, numerous, radially symmetrical , with bell-shaped calyces.
Species hybridize freely.
Petals cream-colored, separate. Petals yellow, fused at base. Stamen filaments red. Prolific, especially in dry years. Pods linear , 8-15 cm long, covered with short, velvety hairs , especially while immature.