Key to the species of Excoecaria in India is as follows:
1a. Plants dioecious, of mangrove or littoral areas; leaves alternate, with basally two glands in the margin at either side of the petiole; male flowers in very dense catkins 2. E. agallocha
b. Plants monoecious, of interior forest areas; leaves alternate or opposite, without basal glands in the margin; male flowers in open racemes or in heads 2
2a. Leaves opposite or at least partly opposite 3
b. Leaves entirely alternate 5
3a. Leaves all opposite, green beneath; inflorescences with one type of flowers only, male inflorescences 3.5 – 22 cm long; fruits slightly depressed and shallowly lobed, usually larger, 1 – 6 cm in diam. 4
b. Leaves alternate or opposite, wine-red beneath; inflorescences with basally a few female flowers and apically many male ones; male inflorescences 1 – 3 cm long; fruits much depressed and deeply lobed, smaller, up to 1 cm in diam.(cult.) E. cochinchinensis
4a. Branchlets mostly flattened or tetragonous; male inflorescences 3.5 – 8 cm long; fruits 1 – 3 cm in diam. 3. E. crenulata
b.Branchlets mostly terete; male inflorescences 5 – 22 cm long; fruits 4 – 6 cm in diam. 5. E. oppositifolia
5a. Leaves larger, 25 – 32 x 8 – 11 cm; petioles 3 – 4 cm long 6. E. rectinervis
b. Leaves smaller, 2.5 – 16 x 1 – 5 cm; petioles 0.2 – 3 cm long 6
6a. Leaves closely and regularly serrulate along margins; lateral nerves close, parallel, conspicuously raised on the upper surface; tertiary nerves closely parallel and running predominantly at right angles to the midrib; fruits 1.5 – 1.8 cm in diam.1. E. acerifolia
b. Leaves distantly repand-serrulate along margins; lateral nerves distant and arcuate, obscure or faint on the upper surface; tertiary nerves laxly reticulate; fruits up to 1 cm in diam. 4. E. cuspidata
Species as per Flora of India Vol 23 (Editors N. P. Balakrishnan, T. Chakrabarty, M. Sanjappa, P. Lakshminarsimhan & P. Singh- by Botanical Survey of India (2012)):
Excoecaria acerifolia Didr.
Excoecaria agallocha L.
Excoecaria cochinchinensis Lour. (Cultivated)
Excoecaria crenulata Wight
Excoecaria cuspidata (Müll.Arg.) Chakrab. & M.Gangop.
Excoecaria oppositifolia Griff.
Excoecaria rectinervis (Kurz) Kurz