The jellyfish tree (Medusagyne oppositifolia) is a critically endangered and unusual tree endemic to the island of Mahé, of the Seychelles. It is the sole member of the genus Medusagyne. The plant was thought to be extinct until a few individuals were discovered in the 1970s.

They are small trees which can reach up to 10 metres tall and have a dense, rounded crown of foliage. The bark is dark and has many distinctive, deep fissures. The leaves are shiny and leathery in appearance with a slightly scalloped edge; they turn bright red with age. Leaves are up to 8 cm in length. The small, white flowers are difficult to see amongst the dense foliage; both male and bisexual flowers are carried on the drooping inflorescence. The gynoecium of the flower resembles the tentacles of a jellyfish, hence the common and generic names of the plant. This plant exhibits many adaptations to dry climate, strange on a moist archipelago. It can withstand drought, and its seeds disperse by the wind. This suggests it has Gondwanan origins. The fruits are green and rounded; the outer coat becomes reddish-brown with maturity and then dries, exposing the seeds within, which are then distributed by the wind.