Alfalfa is an excellent choice for nutrition and is drought tolerant. This perennial can be tricky to establish and maintain. It requires a high pH and control of fungus and insect problems. It is best to find someone to harvest the hay to keep excess residue from building up.
Birdsfoot Trefoil is slow to establish from seed, but is easier to grow on marginal sites than alfalfa. Watch for weed problems in young stands of this perennial.
Chicory is a drought tolerant perennial. It is normally used a companion to white clover to supplement forage in summer stressed clover. It should be used at a rate of 20-25% of the clover mix.
Durana Clover just barely made the list, because it can fade during the hottest driest periods. It is the toughest white clover. Durana has nearly twice the stolon density of ladino clover, ensuring a quick recovery from grazing or drought. During a “normal” year, it can provide forage throughout the summer. It can also tolerate brief periods of flooding.