You can forget the passport and the anti-malaria pills, but you will need some comfortable walking shoes and lightweight clothing when you visit the Palm House at the Royal Botanic Gardens at Kew.
The Palm House was originally designed to be tall and grand enough to accommodate the "princes" of the tropical plant kingdom, in keeping with Kew's image as a royal garden.
It was built between 1844 and 1848 and constructed solely with wrought iron and panes of curved glass. Because of this, it has large areas of lofty, unsupported space and has often been compared to the upturned hull of a ship. It is also described as the "greatest glasshouse in the world". It is now a Grade I listed building and the most important surviving 19th-century glass and iron structure in the world.
It was, though, never intended exclusively for palms and, in 1865, other tropical plants were introduced. Today, it houses a rich diversity of tropical flora and trees, many of which are threatened with extinction in their native habitats, such as the Illume or Sierra Palm, which bears cherry-like fruits and has now nearly died out in the Caribbean and Central America, or the Lagenicaulis or Bottle Palm, which has all but disappeared from Round Island in the Mascarenes.
The Palm House is divided into global regions: the Americas are laid out in the central area, with Africa in the south wing and the Asian, Australian and Pacific rainforests in the north wing. Each captures the multi-layered nature of a typical tropical rainforest with the canopy palms and other trees, and then shorter "under-storey" palms and dwarf palms beneath.
The earthy, woody scents and the damp mist from the humid-ification equipment really do make you feel as though you're deep in the heart of Borneo as you stroll through this towering forest. And, like a real jungle, it can get quite uncomfortable.
It is also authentically green. If you are expecting to see magnificent flowers in a vast array of rainbow colours, you will be disappointed, although the Palm House does contain some flowering trees and shrubs.
Familiar plants such as Henna (Lawsonia inermis), Annatto (vermilion or yellow dye) and banana are on show but the rarer groups, such as the collection of cycads, are more fascinating. These are an ancient group of cone-bearing plants related to conifers. They are not palms, although they resemble them, with their unbranched trunks and huge crown of leaves, and they covered the earth about 180-135 million years ago along with the dinosaurs. Unlike the dinosaurs, however, this lot managed to survive.
Another interesting specimen, brought to Kew from South Africa in 1775, is known as Encephalartos longifolius and is currently thought to be the oldest pot plant in the world. This towering plant is so large it has to be supported with metal scaffolding.
One of the rarest palms is the double coconut or coco-de-mer (Lodoicea maldivica), which is found only in the Seychelles. One of these has been cultivated at Kew since 1850. It is a very slow-growing palm that produces two huge-lobed nuts which are the largest in the plant kingdom.
For an aerial view of the "forest", you need to take a deep breath and climb 50 steps up a spiral stairway to a viewing gallery. From this heart-stopping vantage point, you can look over the vast canopies beneath, from where you half expect to feel the ground shake as some prehistoric monster charges out of the undergrowth. When you consider that this slice of tropical forest would have to quadruple in height to mirror its actual size if it were still in its native country, it really is an awesome sight.
Although the Palm House is undoubtedly impressive, its provision for teachers is appalling. There was a complete absence of information available about individual plants, which is frustrating for any visitor, the information desk had no leaflets and, inside the glasshouse itself, only a few of the plants had boards beside them giving the origin and other relevant details. Most had just a name on a stick. I had to buy a book to accompany my visit. At Pounds 12.50, it was an expensive option.
* The Palm House is open every day at 9.30am except for Christmas Day and New Year's Day and entrance fees are Pounds 4.50 for adults and Pounds 2.50 for children. Group rates available. Details: Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB. Tel 0181 332 5000