The key to the genera of Geraniaceae
1. Flowers actinomorphic, or apparently actinomorphic…….………………..……………………………2
1. Flowers zygomorphic………………………………………………………………………….……………….………….……….6
2. Stamens 5, no staminodes ..……………….………….……………….………………..………….………California
2. Stamens + staminodes 10 or 15 ………………….…………….…….……………………..……………………………3
3. Stamens + staminodes 10 …………….………………….……………….……………..……..…………………………….4
3. Stamens 15 ……………………………………………………………………………………………….…..……………………………5
4. Fertile stamens 10 ………………………………………………….…………..…….……………………Geranium
4. Fertile stamens 5, staminodes 5 …………………………………………………..………………Erodium
5. Stems herbaceous without spines ……………………………………..……..…………………Monsonia
5. Stems succulent, generally with spines …………………………………..……………. Sarcocaulon
6. Flowers with a nectar spur (hypanthium) …………………………..……………………. Pelargonium
6. Flowers without a nectar spur ………………………………………………………….….………………. Erodium
Erodium and California
Erodium L’Hér. ex Aiton
Herbs, rarely small shrubs, annual or perennial, root often a thick tap root, rarely with tubers; plants either monoecious or dioecious.
Leaves entire or lobed to pinnately dissected, often with lobed or dissected leaflets, with or without intercalary lobes.
Flowers (apparently) actinomorphic or zygomorphic; sepals 5; petals 5; fertile stamens 5; staminodes (sterile stamens with no anthers) 5; ovaries 5, fused, normally with 1 seed in each, rarely 2 (in E. gruinum).
Fruit is a dry schizocarp. After fertilisation the style elongates to form the rostrum above the mericarps; at maturity the rostrum, with the mericarps, splits from the base, allowing the seeds in their mericarp and their awn to curl up and spring away from the parent plant or to hang waiting for a passing animal (barbate mericarp in subgenus Barbata) or a breeze (plumose mericarp, subgenus Erodium) to carry it off.
Plant form is mainly of a tap rooted tuft of very short above ground stems, from which annual flowering stems may grow; the annual species are usually of the same form as the annual species of Geranium and Pelargonium: a ground hugging rosette of leaves which send up a single umbel of flowers direct from the crown, then often sending up one to several usually branching flowering stems; some species will stay as a rosette.
Leaves have in the past been used to help define the sections of subgenus Barbata; whether they are entire, or are pinnately divided, or are pinnately divided with intercalary leaflets or lobes; the intercalary lobes (leaflets) are small fragments of leaf on the rachis between the main leaflets.
Flowers are typically held in umbels, often on a branching stem, sometimes directly from the base of the plant; in the species with apparently actinomorphic flowers the upper sepal is always larger and overlapping its neighbours so the flower is basically zygomorphic. In the dioecious species male and female flowers are on different plants and are all found in the eastern Mediterranean area and the Caucasus.
The fruit comprises of the carpel, containing the seed and the awn which when free of the plant is coiled tightly in the lower part. At the base of the carpel are 2 depressions called foveoles. The shape and indumentum of these, and whether they have ridges or furrows beneath together with type of simple or glandular hairs are useful characters for identification
California Aldas, C. Navarro, P. Vargas, Ll. Sáez & Aedo
The genus California separated from Erodium in the Early Miocene period. It can be distinguished from Erodium by lack of staminodes (5 fertile stamens only, no sterile stamens present), mericarp pit perpendicularly disposed with respect to the awn, bristle rims absent and leaves subpalmately lobed.
