All parts of the plant are astringent

The genus Pelargonium derives its name from the resemblance of the shape of the fruit to the beak of a stork, pelargos in Greek. The species name acetosus (Latin), meaning sour, refers to the acid taste of the leaves. The common name sorrel-leaved pelargonium refers to the resemblance of the leaves to those of the herbal plant, sorrel or Rumex acetosa. P. acetosum was first cultivated in the Chelsea Physic Garden in England in 1724.

http://pza.sanbi.org/pelargonium-acetosum

The young leaves and buds can be eaten in salads and added to soups and stews, they have a pleasing, acidic, lemony taste.

http://pza.sanbi.org/pelargonium-acetosum

Africa, Southern Africa, Cape Provinces