Madhuca diplostemon (C.B.Clarke) P.Royen (Family Sapotaceae), a Critically Endangered tree endemic to the Western Ghats of India, was described by Robert Wight in 1848 and rediscovered after a hiatus of 184 years (Shailajakumari et al., 2020, Rheedea, 30, 383–387). It is known from a single mature individual in front of the Ayiravilli Sacred Grove temple near Paravur, Kollam district, Kerala, and < 30 saplings of 2–10 years of age within the Grove. As this species is not held in any ex situ conservation collections, Jawaharlal Nehru Tropical Botanic Garden and Research Institute, with financial support from the Kerala Forest Department, initiated a 2-year restoration programme for the species in November 2022.
Madhuca diplostemon, showing (a) habit of the single known mature tree, (b) fruiting twig, (c) seeds, (d) germinating seeds, (e) planting of seedling by the Hon. Chief Minister of Kerala, (f) seedlings, and (g, h) in vitro seed germination.
The single mature tree faces several threats: the retaining wall and concrete paving tiles around the tree negatively affect its vigor, it displays early senescence of flowers as a result of heat stress, fruit set is low and fruits are predated by fruit bats Pteropus giganteus and birds. Furthermore, as two deities are worshipped beneath the tree, the temple authorities do not allow collection of seeds directly. However, in 2020 we successfully raised seedlings from fallen fruits, of which one was planted on 5 June 2023 (World Environmental Day) by the Hon. Chief Minister of Kerala, Shri Pinarayi Vijayan, at the campus of the Government Model Higher Secondary School in Thiruvananthapuram as an initiative of the ex situ programme for the species. We are currently developing seed propagation techniques to safeguard this species. The seeds are recalcitrant but our germination studies show 70% success, and 80% following treatment with hot water.
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