The gardens proper, which originally contained only about II acres, were subsequently increased to 75 acres, and the pleasure grounds or arboretum adjoining extend to 270 acres.
Including the arboretum, their total area did not then exceed 1 i acres.
Professor Bayley Balfour, F.R.S., the Regius Keeper of the Royal Botanic Garden in Edinburgh, has described an arboretum as a living collection of species and varieties of trees and shrubs arranged after some definite method - it may be properties, or uses, or some other principle - but usually after that of natural likeness.
By common consent the arboretum in the Royal Botanical Gardens at Kew is one of the finest in the world.
To the north of the Water of Leith lie Inverleith Park, the Arboretum and the Royal Botanical Garden.
According to another point of view, an arboretum should be constructed with regard to picturesque beauty rather than systematically, although it is admitted that for scientific purposes a systematic arrangement is a sine qua non.
Recreation grounds include a picturesque arboretum, Reed's Wood and Palpey Park.
In this more general respect, an arboretum or woodland affords shelter, improves local climate, renovates bad soils, conceals objects unpleasing to the eye, heightens the effect of what is agreeable and graceful, and adds value, artistic and other, to the landscape.
There is a fine arboretum in the botanical gardens at Ottawa, in Canada (65 acres).
It was the birthplace of John Claudius London (1783-1843), the landscape gardener and writer on horticulture, whose Arboretum et Fruticetum Britannicum still ranks as an authority.