They are hermaphroditic, actinomorphic (radially symmetrical, like in Geranium) or slightly zygomorphic (with a bilateral symmetry, like in Pelargonium).

When the fruit is mature the style breaks into five (or three) hygroscopically active (ready to absorb water) bristles that curl, causing the achenes to be released.

California lacks filaments without anthers (called staminodes), but the lower half of the five fertile stamens is made much wider by a wing with a rounded top on each side of the narrow higher part of the filament that carries an anther.

Gray) O. Degener Robertianum Picard Robertiella Hypseocharis, with between one and three species, which comes from the south-west Andean region of South America, is considered the sister to the rest of the family.

Some authors separate Hyspeocharis as a monogeneric family Hypseocharitaceae,[10] while older sources placed it in the Oxalidaceae.

The Geraniaceae have a number of genetic features unique amongst angiosperms, including highly rearranged plastid genomes differing in gene content, order and expansion of the inverted repeat.

Pelargonium has its centre for diversity in the Cape region in South Africa, where there is a striking vegetative and floral variation.