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Twining herbs, creeping or floating, often shrubs. Leaves, entire, lobed or deeply divided. Inflorescence axillary, 1 to many-flowered cymes. Calyx variable. Corolla funnel-shaped or campanulate, limb shallowly or deeply 5-lobed, midpetaline bands well defined by 2 distinct nerves. Stamens 5, filaments often dilated base. Ovary 2-4 celled, 4-6 ovuled, style simple, stigma capitate, entire or 2-3 globular. Fruit a capsule, 4 or 6-valved, or dehiscing irregularly. Seeds 4-6.

Key to the species

Serial Key Reference
1a. Leaves deeply 2-lobed;corolla pink or reddish; trailling stem I. pes-caprae
1b. Leaves entire or variously 3 or more lobed, not deeply 2-lobed 2
2a. Leaves pinnately segmented to midrib with linear to filiform, patent segment; corolla salver shaped, red I. quamoclit
2b. Leaves palmately divided or cut in varying degrees or entire 3
3a. Leaves palmately divided or cut into 5-9 segments 4
3b. Leaves entire or shallowly lobed or dentate 5
4a. Sepals long hairy; leaves palmately devided upto the base to 5-9 segments; corolla white I. pes-tigridis
4b. Speals glabrous; leaves palmately divided into 7-9 segments; corolla pale raddish-purple, tube darker inside I. mauritiana
5a. Stems softly prickly or muricate; flowers white 6
5b. Stems smooth or variously hairy, never prickly; flowers of various colours 7
6a. Stamens distinctly exserted I. alba
6b. Stamens included or scarcely exserted I. aculeata
7a. Stems erect, shrubby, 2-small glands at base of midrib, corolla pink or pale purple I. cornea ssp. fistulosa
7b. Stems trailing on ground or floating on water 8
8a. Stems trailing on mud or floating, rooting at nodes I. aquatica
8b. Stem trailing or turning, never floating on water, never rooting at nodes 9
9a. Stamens exerted; sepals at least the onter ones with a recurved awn 10
9b. Stamens included; sepals obtuse, mucronulate, never recurved awn 11
10a. Corolla white, tube straight, 6-12 cm long I. alba
10b. Corolla scarlet, tube curved, 3-4 cm long I. hederifolia
11a. Flowers in a dense head, enclosed by a large, foliaceous boat shaped bract; corolla 3 cm long, violet or pink I. pileata
11b. Flowers not in head or enclosed by a boat shaped bract 12
12a. Corolla white or pale yellow; darker midpetaline bands and dark purple eyes I. obscura
12b. Coralla of various colours, not white or pale yellow 13
13a. Corolla tube suddenly contracted at 1.5 cm obove base; corolla 9 cm long, reddish purple to pale purple I. illustris
13b. Corolla tube gradually narrowed towards base 14
14a. Stems mostly prostrate or trailing on ground 15
14b. Stems mostly scandent or twiner 16
15a. Stems with milky juice; roots tuberous; a cultivated crop I. batatus
15b. Stems without milky juice; root not tuberous; a trailer of littoral habitats I. littoralis
16a. Peduncles flattened at top; corolla 3 cm long, salver-shaped, light purplish or white tinged I. maxima
16b. Peduncles not flattened towards tip 17
17a. Sepals patently hirsute or bristly hairy 18
17b. Sepals softly hairy I. indica
18a. Corolla pale blue or bright blue I. nil
18b. Corolla purplish blue I. purpurea