Portulaca Plant - 24 Best Drought Tolerant Plants That Grow In Lack Of Water : Moss rose, portulaca grandiflora, is a drought and heat tolerant annual native to hot, dry plains in argentina, southern brazil, and uruguay.this herbaceous plant in the purslane family (portulacaceae) is cultivated throughout the world as a garden annual for its showy flowers that bloom all summer long with little care.