Medusagyne oppositifolia, the jellyfish tree, is a critically endangered and unusual tree endemic to the island of Mahé, of the Seychelles. It is the only member of the Medusagyne genus of the Ochnaceae family of tropical trees and shrubs. The plant, thought to be extinct until a few individuals were found in the 1970s, gets its common name from the distinctive jellyfish-like shape of its dehisced fruit. 
They are small trees which can reach up to 10 m (33 ft) tall and have a dense rounded crown of foliage.
The genus Medusagyne* is in the family Ochnaceae, e.g. in the Angiosperm Phylogeny Group classification, though it is sometimes in the monogeneric family Medusagynaceae. The small tropical American family Quiinaceae is also included in this broad concept of Ochnaceae.
The tree inhabits exposed granite slopes, at present all locations are within 2 km (1.2 mi) of the sea.
The jellyfish tree presents a conundrum in that the seeds seem unable to germinate in the wild; no young plants have been observed in the natural stands.
Three of the existing populations of jellyfish tree on the island on Mahé (Bernica, Copolia and Mt. Jasmin) are protected within the Morne Seychellois National Park. Although seedlings have been grown in a number of botanic gardens, many problems remain and a conservation priority must be further research into the reproductive biology of this intriguing species before any effective Action Plan for its future can be devised.