Palms

Palms are hugely important to us, providing many of the basic necessities of human life such as food, drinks and medicines as well as materials for construction, utensils and crafts.

Identifying palms

70% of palms are found in tropical rainforests, one of the most threatened habitats on earth. In some habitats, they can be a dominant feature of the vegetation.

The distinctive growth form of palms makes them instantly recognisable, even to the uninitiated. The leaves of palms are either pinnate (feather-shaped) or palmate (fan-shaped), and typically sit on top of a column-like trunk.

The palm stem usually starts its growth around ground level, increasing in diameter, but not in height until it reaches its maximum. It then begins to grow upwards forming a uniform cylinder. Palm trunks therefore have a very different internal structure to familiar timber trees such as oak and do not have annual growth rings. Each stem has a single growing point at its apex; if this is destroyed the stem dies. However, many palms branch at the base and build up a clump of stems.

Palm uses

Palm products include palm oil, coir fibre, carnauba wax, rattan and true sago. Because these plants are so useful, many wild stands are overexploited and some species are approaching extinction.

Tahina spectabilis in Madagascar Image: John Dransfield

Palm discoveries at Kew

Kew botanists are actively exploring for palms in remote parts of the tropics, such as New Guinea and Madagascar, and are finding many that are new to science. For example, in recent years, our experts have discovered more than 20 new palm species in Madagascar's threatened forests.

Discovering the 'self-destructive' palm

Most exciting among these was the new 'self-destructive’ palm, which was named and described officially in early 2008.

Spotted first by a family out walking in a remote part of the island, this palm stood out because of its striking lifecycle. Forming huge trees with leaves up to 5m in diameter, the palm grows to dizzying heights before the tip of the stem bursts into a candelabra of branches bearing thousands of tiny flowers that are visited by countless insects and birds. After fruiting, the entire tree collapses and dies.

Materials from the new palm were sent to Kew and studied by our botanists who concluded that the palm was not just a new species, but an entirely new genus. DNA analysis in Kew's Jodrell Laboratory later confirmed this.

With fewer than 100 individuals surviving, the plant, named Tahina spectabilis, presents huge challenges to conservationists. Kew scientists are working alongside locals to protect the area it was found in. Seeds have been sent to Kew’s Millennium Seed Bank for research, and also to other botanical gardens around the world where it is hoped that the plant will thrive.

Origin of species

A collaborative team led by Kew researchers have brought a dramatic evolutionary case-study to light on the remote Pacific Island of Lord Howe. This tiny speck of land, a remnant of a volcano that erupted seven million years ago in the Tasman Sea, is home to two palm species in the genus Howea, including H. forsteriana, one of the commonest pot plants in the world.

Howea palms on Lord Howe Island Image: William Baker

Though closely related, the differences between the species, in their leaves and flowering structures, are clear. That two such close relatives can occur on such a tiny island is dramatic.

Using a combination of DNA and fieldwork studies, the team demonstrated that the Howea species evolved sympatrically (meaning without geographic isolation), a highly controversial finding among biologists, who regard geographical isolation as a much more likely cause of species formation. This discovery, which is already featured in biology textbooks, is now the basis of a growing collaborative research programme of the origin of species.

Kew’s palm conservation work in Madagascar

With about 170 species, 164 of them found nowhere else on earth, Madagascar’s palms are of global importance. Being visually spectacular and prized by horticulturalists they suffer, like orchids, from habitat loss and over-collection.

Through the Threatened Plants of Madagascar Appeal, we have been able to build on our knowledge of Madagascar palm diversity, to accurately assess the degree of threat that each species faces so that conservation strategies can be more accurately prioritised. Using geographical information systems (GIS), we have been able to map not only where the species occur, but also the areas where they could potentially grow, which helps to set objectives for exploration to build understanding of how palms may respond to global change.

With Australian collaborators, we have also focused on some of the most threatened species, such as Beccariophoenix madagascariensis, Tahina spectabilis and Voanioala gerardii to gain a more detailed understanding of their conservation needs using genetic and population data.

The interior of Kew's famous Palm House

Where to see palms at Kew

Kew’s iconic Palm House, which creates conditions similar to tropical rainforest, is home to possibly the most diverse collections of palms to be found in a glasshouse anywhere in the world, and around a quarter of the palms housed here are threatened in the wild. Here you will find the well-known coconut and a number of rattans (climbing palms). Also look out for the coco-de-mer or double coconut (Lodoicea maldivica) with its record-breaking seed – the largest in the world – and the vivid red stems of the sealing wax palm.

The great central dome of the Palm House is home to the tallest of our palms (it is impossible to restrict their height without killing the growing point, or ‘heart’ of the plant). The many-stemmed peach palm (Bactris gasipaes) is often felled for its edible heart – the ‘coeur de palmier’. Also here are the babassu (Attelea speciosa), the fast-growing queen palm (Syagrus romanzoffiana), the American oil palm (Elaeis oleifera) and the pantropical coconut palm (Cocos nucifera), which actually fruits at Kew.

The Temperate House is home to possibly the world’s tallest glasshouse plant, a Chilean wine palm (Jubaea chilensis) raised from seed in 1846. Other palms worth seeing include specimens of Livistona chinensis and Chamaerops humilis, both planted by George V in 1926.

References:

Savolainen, V., Anstett, M.-C., Lexer, C., Hutton, I, Clarkson, J.J, Norup, M.V., Powell, M.P., Springate, D., Salamin, N. & Baker, W.J. (2006). Sympatric Speciation in Palms on an Oceanic Island. Nature 441: 210–213.

Babik, W., R.K. Butlin, W.J. Baker, A.S.T. Papadopulos, M. Boulesteix, M.-C. Anstett, C. Lexer, I. Hutton, V. Savolainen. In press. How sympatric is speciation in the Howea palms of Lord Howe Island? Molecular Ecology 18: 3629–3638.

Shapcott, A., M. Rakotoarinivo, R. J. Smith, G. Lysakova, M. F. Fay, and J. Dransfield. 2007. Can we bring Madagascar's critically endangered palms back from the brink? Genetics, ecology and conservation of the critically endangered palm Beccariophoenix madagascariensis. Botanical Journal of the Linnean Society 154:589-608.