Geranium is a genus in the Geraniaceae family of around 400 species found in temperate regions. The name Geranium means "crane" in Greek, and the common English name of many species is "crane's bill" although this may be a reference to the distinctive seed capsules. Geraniums should not be confused with the plants the horticultural trade refers to as "Geraniums", which are species of Pelargonium. Geranium species have 10 fertile stamens. Pelargonium species also have 10 stamens, but they are not all fertile. Only 1,2,3,4,5, or 7 are fertile.
Geranium maculatum is known as 'Wild Geranium' and is native to the East of North America. The high tannin content of its rhizome led early settlers to use it for tanning hide. Extracts from the rhizome are also used as herbal medicines.
Geranium oxonianum is a hybrid of Geranium endressii and Geranium versicolor. There are many named cultivars and the vigorous plants are common cottage garden hardy geraniums. The typical height is 18 inches and spreading rhizomes mean the plants form large clumps. New plants can easily be propagated from pieces of rhizome. Photographs by David Pilling show characteristic Geranium palmate leaves, rhizome and seed production (black spot at the base of the 'bill').
Geranium tuberosum is a tuberous species that originates from southern Europe into Asia Minor. It is dormant in summer. It has small pink/blue flowers borne above quite nice foliage. It is adaptable and does well in a sunny, well-drained position. It is reported to be hardy in colder climates.