General description:- Herbs, or rarely small shrubs with soft stems.
Leaves:- Stipulate, usually lobed or divided, and sometimes more or less compound.
Flowers:- In cymes, umbels or spikes, 5-merous, actinomorphic or somewhat zygomorphic. Sepals 5, free; petals 5, free; stamens obdiplostemonous in two whorls of 5, some of them sometimes reduced to staminodes. Ovary superior, of 5 united carpels, separating in fruit into 5 1-seeded mericarps; styles united in flower, sometimes separating in fruit.
ERODIUM
General description:- Annual to perennial herbs usually with hermaphrodite flowers, rarely with unisexual flowers, the male and female flowers on different plants (dioecious).
Leaves:- Mostly opposite, usually longer than wide, lobed, the lobes extending from about a quarter to half-way towards the midrib, but not separated into distinct leaflets (pinnatifid to pinnate), or rarely undivided, usually with appressed hairs.
Flowers:- Inflorescence an umbel (rarely reduced to a single flower), subtended by 2 or more usually thin,dry (scarious) bracts. Flowers actinomorphic or slightly zygomorphic. Stamens 5, opposite to a sepal (antesepalous), with a nectary at the base of the filament, alternating with 5 scale-like staminodes (infertile, often modified, stamen). Stigmas 5, thread-like (filiform).
Fruit:- Mericarps not split open to release their seeds (indehiscent), separating from the base upwards, retaining during dispersal the outer part of the style as a long beak, which in most species becomes twisted into a spiral at maturity, the pitch of the spiral varying with the humidity.
Key features:-
1) Leaves pinnately divided or lobed.
2) Beak of mericarp spirally twisted at maturity.
GERANIUM
General description:- Herbs.
Leaves:- More or less orbicular in outline, palmately (rarely ternately) lobed or divided, many or all of them basal leaves that usually have long petioles; the cauline leaves, if present, have progressively shorter petioles and lamina often with fewer lobes usually opposite near base of stem, but often alternate in inflorescence.
all leaves bear rather short, appressed hairs on both surfaces;
Flowers:- Inflorescence cymose; ultimate peduncles usually 2-flowered. Flowers actinomorphic. Stamens all fertile, or rarely 3-5 reduced to staminodes. Stigmas 5, filiform. Sepals, hairy, obtuse to subacute, and mucronate or aristate.
Fruit:- Mericarps usually dehiscent, separating from the base upwards, usually retaining outer part of style in the form of a long beak, of which the apex remains for a while attached to the central axis formed by the still coherent inner parts of all 5 styles.
The term lobe is used to indicate a primary division of the leaf, segment a division of a lobe. Measurements of sepals refer to the fruiting condition, and include the arista.
Key features:-
1) Flowers in cymes or umbels.
2) Stigmas free, linear.
3) Leaves palmately (rarely ternately) divided or lobed.
4) Beak of mericarp straight or curved in a simple arc, sometimes absent.
G. TUBEROSUM Group
General description:- Perennials with short, thick, often tuber-like rhizome.
Stem:- Single, 20-60 cm, erect, pubescent, with 0-2 pairs of cauline leaves in addition to the pair of large, leaf-like bracts at the base of the inflorescence, which consists of 2 main branches and sometimes a smaller terminal branch between them, each branch terminating in a corymbose cyme.
Leaves:- Basal leaves divided for at least 95 % of the radius into 5-9 lobes, which are variously toothed, lobed or pinnatisect. Cauline leaves (if present) and bracts also deeply lobed, but the lobes narrower and less deeply segmented.
Flowers:- Petals broadly obovate, deeply notched at the apex (emarginate), purplish-pink.
Fruit:- Mericarps hairy, without ridges.
Key features:-
1) Peduncles 2-flowered.
2) Pedicels with long glandular hairs.
3) Leaves divided to the base.
4) Rhizome short, often tuberous.