Huntington Botanic Gardens is magnificent. Comprising no fewer than 15 specialized gardens set on 54 hectares of the 86-hectare San Marino estate a mere 20 km northeast of downtown Los Angeles, it is home to an astonishing 14,000-plus species of plants.

In particular, the Desert Garden there must rank as the world's best. However, the other fine gardens, including a Zen Garden, a Camellia Garden and a Rose Garden, in whose Tea Room many visitors enjoy an English cuppa, are all outstanding in their own right too.

In the grounds -- first opened to the public in 1928 -- there is also an orange grove, maintained as a reminder of the estate's past: It was formerly a 250-hectare citrus farm owned by one J. de Barth Shorb. All that -- except the orange grove -- changed when New York-born railroad and real-estate magnate Henry Edwards Huntington bought the estate and moved there to retire in 1906.

Then aged 60, he devoted himself to collecting art and books -- both of which are now world-class collections in fine buildings on the same site. After selling large tracts of the farm and reducing the estate's area to its present size, he appointed a botanist named William Hertrich to work there and create the gardens.

Apparently, Huntington once asked Hertrich what he could do with a dry, sun-baked, over-drained piece of ground close to the art gallery. Hertrich suggested growing desert plants, and so it was that in 1908 the botanist returned from a trip to Arizona, Texas and New Mexico with three railroad trucks full of cacti and succulents. Then, when he went off collecting in Mexico four years later, he brought back so many specimens that the Desert Garden had to be enlarged.

Amazingly, his 1908 haul included nine fully grown specimens of the giant saguaro cactus (Carnegiea gigantea), which is the largest of all cacti and lives from 200 to 300 years. These cacti, of which there is only one species, are native to the southwestern United States and Mexico. They bear white flowers 12.5 cm in diameter between May and June, and their fruit has for centuries been used to make cactus jelly.

Though saguros are the world's tallest cacti, the specimens here are actually topped by a Cereus xanthocarpus from Paraguay. Yet another tropical American native, the silk cotton tree (Ceiba insignis), with its swollen trunk bristling with stout thorns, is perhaps the greatest visitor attraction -- especially when its white-to-yellow flowers open before any of its palmate leaves have unfolded in early spring. The fibrous kapok surrounding the tree's large seeds has long been used by Amazonian tribes to make arrow-proof jackets. Eight times lighter than cotton and sound-absorbing, kapok is also used as filling in lifebelts and in acoustic insulation.

As visitors to the Desert Garden soon learn, plants adapted to grow in very dry regions are known as xerophytes and often come in weird and wonderful shapes. For instance, the spines on cacti are branches that have evolved to reduce the surface area exposed to both broiling days and cold nights, and also to protect the water-storing part of the plant from predators. Meanwhile, below ground some cacti have developed other ways of storing moisture. The dahlia cactus (Wilcoxia poselgeri) has only a few stems above ground, but the root system is tuberous just like the common dahlia.

The Southern California climate is ideal for growing aloes, a large genus of the lily family native to Africa. At Huntington, visitors can gaze in awe at the Aloe bainesii, a tree-like variety native to southern Africa that can reach 18 meters, or admire the tree aloe (Aloe arborescens) bursting forth with bright vermilion to clear yellow flowers between December and February. Aloe vera, introduced to Mexico by Spanish missionaries, is there too, and is well-known for its use in cosmetics and pharmaceuticals.

Among all these desert delights is a splendid group of golden-barrel cacti (Echino cactus grusonii), which in their slow-growing lives never top 80 cm in height, but can reach 130 cm in diameter. Euphorbia grows well here too, and visitors in June can enjoy the attractive red flowers of the crown of thorns, or Euphorbia milii from Madagascar.

Moving on from the Desert Garden, visitors will encounter some fine specimens of Mexican swamp cypress or Montezuma cypress (Taxodium mucronatum), close relatives of the bald cypress (T. distichum) common in the eastern U.S. swamps. Seeds of these trees, which grow at the edges of streams or on marshy land in the hills of southern Texas and temperate Mexico, were brought back from Mexico by Hertrich in 1912.

Meanwhile, those inclined to pause for a little contemplation could do no better than stop off at the Zen Garden, a replica of that at Daitokuji Temple in Kyoto. Like the original, this is a work of art. There is also a fine bonsai collection at its entrance and nearby a lovely traditional Japanese house where tea ceremonies are held.

The Camellia Garden at Huntington was begun in 1942 and opened to the public in 1951. Planted in the shade of Californian oaks, it is now stocked with some 1,500 cultivars. In February, it was awarded the title International Garden of Excellence by the Fort Valley, Georgia-based International Camellia Society.

As if all that were not enough (and there's far more beside), just by the main gate is one of the best cycad and palm collections in the United States. Here, alongside the cycads, true survivors (along with gingko and magnolia trees) from the time of the dinosaurs, you can also see the rare Cretan palm (Phoenix theophrasti) and the Queen palm (Syagrus romanzoffiana) from Brazil, which, with its characteristic swollen trunk, can reach 10-20 meters in height.

And remember there're those collections of art and books as well. Truly a magnificent place.