Inverleith House, listed category B, is a classical mansion of three storeys, built in 1774 for James Rocheid to a design by David Henderson. Two pavilions, situated to the north of the house, are linked to it by diagonal screen walls. Alterations to the original house were made by W. Robertson in 1877 and again recently. Until 1984, the main building housed the Gallery of Modern Art. It is presently being developed as a Visitor and Exhibition Centre for the Botanic Garden. The western pavilion houses the public tea room for visitors to the Garden. The former Herbarium building by David Cousin, was built in 1843 and was the Exhibition Hall of the Royal Caledonian Horticultural Society. The modern Herbarium building by R. Saddler, which also houses the Library and Administrative offices received a Civic Trust Award when opened in 1964. The Tropical Palm House was opened in 1834 and is connected to the larger Temperate Palm House built in 1858, which is thought to be the tallest glasshouse in Britain. The new Exhibition Plant Houses were opened in 1967. The seven interconnected houses provide a range of distinct climatic regimes and are landscaped as habitats appropriate to the plant life which has been established in them.
Until recently, several pieces of modern sculpture were sited within the Garden, mainly due to its associations with the Gallery of Modern Art. Since the relocation of the Gallery, most of these have been removed. Those which remain include one on the edge of the Heath Garden by Barbara Hepworth. The Linnaeus Monument is indicated on the OS map of 1852 to the west of the laboratories and was relocated to its present position in 1967. The gatepiers to the south-west, at the entry to Arboretum Avenue, are early 18th century, broken pediment type, with grotesque lions.
The Garden has been developed into several distinct areas:
The Heath Garden, situated in the south-east corner of the Garden, has been developed since 1933 and contains plants from the genera Erica and Calluna in the family Ericaceae. Most of the plants are low growing and provide colour from June-October with interest provided in winter months by cultivars of Erica heracea.
The Rock Garden, situated to the west of the Heath Garden, was originally established by 1852 in a form indicated on the OS map of that year. The present Rock Garden was originally designed by Sir Isaac Bayley Balfour and was built between 1908 -1914 with conglomerate rock from Ben Ledi, Perthshire, and sandstone from Dumfriesshire. Since 1970, it has been completely resoiled and replanted. Plants in the rock garden have wide ranging origins from hot Mediterranean Regions to cold permafrost regions. Plant genera include Cytisus, Genista and Potentilla and dwarf forms of Rhododendron and conifers as well as alpine plants such as Saxifraga, Allium, Pulsatilla and Gentiana including Gentiana 'Inverleith' (a hybrid of G. farreri and G. veitchiorum). Rare plants include fine specimens of the willow Salix boydii. A stream and waterfall flowing through the rock garden is pumped from the pond which lies to the north, beyond the Old Herbarium building.
The garden around the Pond is a naturally wet area which is fed by springs. It was transformed in the course of Garden improvements between 1820-23 and is the habitat for the many hardy aquatic and marsh plants which have been established around its margins, including Nuphar lutea, Lysichiton americanum, Arum maculatum Phormium tenax and Gunnera manicata. Specimen trees around the pond include willow, swamp cypress and ornamental maples.
The Woodland Garden is situated to the west of the Rock Garden beneath a canopy of mainly coniferous trees. Rhododendrons are well established within the area and include numerous species which flower from January to late August. Worthy of note are R. mucronulatum, R. falconeri, R. basilicum, R. praestans and R. hippophaeoides. The Rhododendrons provide shelter for the many other species grown within the woodland canopy, including Camellias, Magnolias, Cotoneasters, Hydrangeas and Liliums with ground cover planting of Meconopsis, Primulas, and Hostas.
The Peat Garden continues from the northern edge of the Woodland Garden. It was originally a 'rootery' with peat dumped to conceal an unsightly area of old tree stumps. Onto this base, dwarf evergreens were established. The area has now been reconstructed using peat walls to provide terraces where Cassiopes, dwarf Rhododendrons, Gaultherias, Pernettyas and Schizocodons are grown, some of which have creeping roots to help stabilize the terraces. Liliums, orchids, Primulas and trilliums grow between the shrubs, as well as Meconopsis and Ourisias, all of which add colour and interest to this relatively shaded area.
The Arboretum lies to the north-west of the Peat Garden on the south-facing slope of the hill on which Inverleith House stands. It is the largest section of the Garden. Originally, it was intended that all members of a single genus were laid out together but this order has been partially lost over the years for a variety of reasons. In 1981, Alan Mitchell surveyed 158 trees, most of which can be found in the Arboretum; amongst them were 15 types of oak, including Quercus lusitanica v. serratifolia and Q. velutina, and 15 species of birch (Betula) and 22 species of Acer, including A. acuminatum and A. rufinerve. Of particular interest is Tetracentronsinense, the only member of the family Tetracentraceae which was formerly part of the family Magnoliaceae. The trees are attractively laid out on lawn enabling the visitor to walk through the Arboretum. The situation of the Arboretum on the hillside enables good views to be gained of it from all angles.
The Rhododendron Walk extends from the West Gate around the edge of the hillside on which Inverleith House stands. It passes the lawn in front of the house, the site of the 19th century formal garden and, more recently, the Sculpture Court of the Gallery of Modern Art. Many of the species grown in the Woodland Garden are found here, providing shelter for the many herbaceous species which grow in association with them, including Paeonia lutea var. ludlowii, Rodgersia henrici, Helleborus corsicus and various tender plants including Desfontainea spinosa. Between the Rhododendron Walk and the Exhibition Plant Houses is the Azalea Lawn which provides a magnificent display in spring/summer. A wide range of Azaleas is represented, ranging from the early flowering mollis varieties to the ghent hybrids and the occidentale hybrids which flower into July. Additional interest is provided by specimen Rhododendrons and trees from the family Rosaceae.
West of the Azalea lawn on the north-facing edge of the hill is the Copse. It lies on an extremely exposed site and protection is provided by shelterbelts of pines and hollies. Many mature trees are well established in the area as well as specimens of Acer palmatum 'Senkaki', Eucryphia glutinosa and Nothofagus species. They all contribute shade and shelter to the understorey which is largely composed of Rhododendrons.
A fine mature beech hedge lies beyond the northern boundary of the Copse. A broad herbaceous border runs along the south side of the hedge and, on the north side, is the Demonstration Garden. It aims to use living plants to introduce the visitor to a number of basic botanical and horticultural principles including plant classification, methods of reproduction, selection and hybridisation. To this end, the garden is laid out in a series of beds, each with an individual topic, eg The Rose Garden which depicts the development of the rose, Culinary Herbs, Medicinal Herbs, Groundcover Plants, and plants from the Scottish Flora grouped according to their taxonomic classification.