River palm

The Essence

"Ravenea musicalis is a Madagascan palm that grows standing in flowing river water, and is widely described as the only truly aquatic palm. Dransfield and Beentje's 1995 Palms of Madagascar account calls it the only true Madagascar water palm, and possibly the only palm in the world of which the seeds sprout under water. Its fruits are orange, 17-23 by 14-19 mm, with a spongy rather than fleshy mesocarp that makes them buoyant. They float but open at the slightest bump, releasing a seed that has already sprouted inside the fruit; the liberated seed sinks and can quickly establish itself on the river bottom, its curved scale leaves apparently helping it catch on protuberances so that it is not easily washed away. Seedlings and juveniles develop entirely under water, their flaccid leaves trailing downstream in the current and becoming rigid only once the stem emerges above the surface - a reproductive cycle that Wikipedia notes resembles a mangrove's more than a palm's. The monograph separates it from all other Ravenea by its habitat and habit, its extraordinary floating fruit with its spongy mesocarp, the number of scale leaves on the seedling, and the lack of hard fibres in the outer wood. Parts of the plant are still undescribed: the original account lists staminate flowers as unknown. Cultivation is notoriously difficult - PACSOA reports that few plants survive past the small seedling stage, and Trebrown that the species has proved difficult to maintain in cultivation."

Henk Beentje described the species as new to science in 1993 (Principes 37: 199), and Palmpedia notes the discovery caused a sensation in the palm world as the only truly aquatic palm. The 1995 Kew monograph rated it Vulnerable and recorded no uses known to local people; later fieldwork superseded both points. Hogg and Henshall's survey (Palms 58(3): 135-142, 2014) counted 1,797 mature individuals across the three known rivers - Belavenoka (1,036), Vatomirindry (726) and Ebakika (35) - and argued this could improve the status from Critically Endangered to Vulnerable (D2), while warning that rapid increases in habitat loss and exploitation could reverse the gain. They record that villagers use the palm for food (palm heart) in the lean season and for building temporary canoes in the wet season, and that riverside land has been converted for cassava, sugar cane and rice. The IUCN assessment adds harvesting of plants and seed for the horticultural trade as a further threat.