When I arrived at Los Angeles airport in June, my friend Joan Juenemann was there to meet me. My stay in California was to be only three days, but Joan had kindly prepared an itinerary taking in one garden with its own unique character each day.

Many gardeners like to specialize, whether in bonsai, roses or alpines, to name but a few. My personal area is trees, so for me a visit to Los Angeles City and County Arboretum was just great. In particular, one of the joys of this wonderful place is being able to see the specimens growing to their maximum height and width without having to be pruned because of buildings or overhead cables.

The 50-hectare arboretum opened to the public in 1948 and now has more than 5,000 plant species from around the world. With such a wealth of plant life, I soon realized that a day is not enough to see everything.

The mild Southern California climate is ideal for growing trees and shrubs from Australia, South Africa and South America, and, due to the nearby San Gabriel Mountains, from where cooler air blows down in winter, even birches.

At the northern end of the arboretum, in the Australian section, there are magnificent stands of eucalyptus trees. In fact, much of the Southern California skyline is dominated by gum trees, as the genus Eucalyptus is commonly known. With more than 600 species, this very large genus of evergreens includes not only trees but also shrubs and mallees, which are bush-fire adaptations characterized by short-lived stems produced from a swollen base.

As well as being the habitat and food source for koalas, eucalyptus are some of the tallest trees ever known -- one Australian mountain ash (E. regans) north of Melbourne towers over 97 meters. Bees feeding on flowers of the narrow-leafed ironbark, or red ironbark (Eucalyptus crebra), which can reach to over 30 meters, are said to produce the world's best honey, while the tree's timber is hard and excellent for both fuel and furniture.

Another Australian native, from the island continent's northern and eastern zones, is the flax leaf paperbark, sometimes known as "snow in summer." Specimens of this tree (Melaleuca linariifolia) are here, too, smothered with white flowers in June. This is a tough tree that sheds its bark in strips, and, as it can withstand heat, wind, poor soil, limited moisture and salt air, it does particularly well here.

Skipping across continents, just outside the arboretum's main entrance is a beautiful specimen of the pink trumpet tree (Tabebuia impetiginosa). An evergreen native to Brazil, this is said to yield South America's most durable timber, known as lapacho, which is used for making cabinets and even ball bearings. The botanical name comes from its native Brazilian name, tabebuia, and for untold ages Amazonian tribes have used the bark of some species as a source of medicine for cancer and malaria -- a medicine pharmaceutical firms have now patented.

Tabebuia belongs to the Bignoniaceae family, and in Southern California in May or June you can't fail to see the lilac-colored flowers of another member of the family, the Jacaranda tree (Jacaranda mimosifolia). Native to Argentina, jacarandas may only reach 15 meters or so, but their magnificent trumpet-shaped blooms make them one of the most beautiful flowering trees I have ever seen.

Jacarandas are fast-growing and can be evergreen or semi-evergreen, though the estimated 50 species, all native to South America, require a frost-free environment. Jacaranda is a Portuguese name, which in turn was derived from the name given by the native Brazilian people. The species name (J. mimosifolia) comes from the leaves' close resemblance to those of the true mimosa, Acacia baileyana.

From Asia, one of the arboretum's most outstanding trees is the deciduous Indian horse chestnut (Aesculus indica), which is native to the northeast Himalayan region. Its heavy growth of compound, palmate foliage (with each leaf comprising five to nine leaflets) makes it a magnificent sight in spring.

Roughly in the center of the grounds is a large body of water known as Baldwin Lake. Surprisingly enough, this is one of the few natural ponds in Southern California, being supplied by underground springs.

On the lake's south shore are some historical buildings, including the Hugo Reid Adobe. This small building is a fascinating link to California's past, since it is a reconstruction of the home of Hugo Reid (1810-52), a Scottish adventurer and naturalized Mexican citizen who was the first owner of Rancho Santa Anita, which sprawled over 5,392 hectares, including the comparatively tiny portion where the arboretum now stands.

Reid applied for provisional title of the land in 1839. To fulfill ownership requirements, Reid and his Native American wife Victoria had to agree to plant crops, run cattle and construct a house on the property, which they did using adobe (sun-dried bricks made from clay, water and a straw binder) and tar-covered rawhide for the roof.

Nearby the Reids' adobe home are reconstructions of kiys, the willow-framed, reed-covered huts in which the area's indigenous Tongva people lived. Acorns from the mesa oak (Quercus engelmannii) were a staple food for these nomadic hunter-gatherers, who were renamed the Gabrielinos by the Franciscans Fathers who founded the San Gabriel Mission in 1771. On Tallac Knoll in the arboretum is one of the last natural stands of these trees.

But it's not just trees and fascinating history at this wonderful arboretum. Close to the main entrance is a demonstration corner where it is also worth spending some time. Sponsored by the horticultural journal Sunset Magazine, this is where, in 1956, a former director of the arboretum decided to allocate an area for "idea-provoking" designs for domestic gardens. In 1998, eight new model gardens were made in a 1-hectare area there, linked by a serpentine pathway. Now, visitors can get ideas on how to create a garden, a patio, outdoor fireplaces, water features, etc.

Also close to the entrance are a library and lecture hall, where talks and horticulture events are often held. The arboretum is home to some boisterous peacocks and peahens, too, and there is a bird sanctuary on site as well.

With so much to do and see, it will come as a relief to many to know that a tram service is available for those who wish to rest their legs.