View photos of the edible and medicinal plant Rumex hymenosepalus (Wild rhubarb), profiled in Medicinal Plants of the American Southwest, Southern California Food Plants, Sonoran Desert Food Plants, and Wild Edible Plants of New Mexico.

A passage from Medicinal Plants of the American Southwest:

Wild rhubarb (roots) is used topically for its astringency. External preparations are tightening to surface tissues and will lessen skin irritation and redness from burns, rashes, and scrapes. The plant, being moderately hemostatic is well applied to superficial cuts. Although symptomatic in effect, it can be almost miraculous in limiting the spread of stress or chemical sensitivity rashes. 

A passage from Southern California Food Plants:

The young and succulent flowering stalks are cut, peeled, and eaten as they stand. They are tart–tasting, hydrated,
and refreshing. The young–emerging leaves are eaten after a boil and water rinse.

A passage from Sonoran Desert Food Plants:

Due to their high tannin content, the tubers can be poulticed and applied to cuts and scrapes. The mature leaves will also make a soothing poultice for sunburn.

A passage from Wild Edible Plants of New Mexico:

Along the Rio Grande corridor, between El Paso and Albuquerque, northwestern and southwestern parts of the state hold the greatest concentrations.