The power of horticulture.

In organising the Museum of Modern Art's current exhibition, Groundswell: Construeting the Contemporary Landscape, Peter Reed, a curator in the Department of Architecture and Design, recognises the pivotal role of landscape architects whose post-industrial landscapes are reshaping cities worldwide. Twenty-three different sites--urban parks, town squares and one cemetery--are conveyed imaginatively in splendid new galleries through models, photographs and videos, and, borrowing Humphry Repton's nineteenth-century technique of persuasion, before and after views. Landscape architecture as a term signifies the challenge of the profession between the permanency of structure and the transience of nature. Though often perceived as being secondary to architects, the plans on view make clear that the survival of urban centres is dependent on the design ingenuity and horticultural expertise alone of landscape architects who create new places where people may congregate for sheer pleasure and, dare one say, spiritual refreshment.

As with any major shift in contemporary design and here it is the complexities of salvaging industrial wastelands--those that succeed best are inspired by lessons from the past. Not surprisingly, in describing his tree plantations, meadows and marshes for a five-mile stretch along the Garonne riverfront across from Bordeaux's formal centre, Michel Desvigne of Paris invokes the name of Frederick Law Olmsted, who designed New York's Central Park on swampland. (Olmsted himself was inspired by Sir Joseph Paxton's Birkenhead Park outside Liverpool, also originally swampland.) Desvigne's concept of creating alluvial forests for future reclamation can already be seen on the Greenwich Peninsula in London.

Within this former flat industrial zone on the banks of the Garonne, Catherine Mosbach, also of Paris, has already completed the Bordeaux Botanical Garden, a sleek Modernist design that makes a virtue of biodiversity by arranging thematic plantings in refreshingly contemporary forms. Surrounded by a robust wall of split tree trunks, the site features a serene water garden, an irregular grid of squared-off basins sparsely planted and framed by paved walks, a central allee of 11 plant habitats that appear like gigantic chunks of earth removed from their respective regions, and long straight rows of agricultural crops interspersed by linear concrete pavers embedded in grass.

Seattle-based Kathryn Gustafson has been proposing some of the most original solutions for shaping land, with no less than three projects in the show. Beginning with stripped-down models demonstrating the contours of the site plan, this Versailles-trained landscape architect 'builds different teams for her far-flung locations. For the Shell Petroleum Headquarters in residential Rueil-Malmaison, France, she concealed underground parking with a series of lush rolling grass berms separated by the sharp corners of limestone walls as if a green lava flow had buried the rest of the building.

[ILLUSTRATION OMITTED]

In Chicago, Gustafson's metal armatures framing 15ft hedges in the Lurie Garden within the new lakefront Millennium Park appear from a distance to support Frank O. Gehry's dramatic, undulating bandshell. The garden itself, with a central arched boardwalk path and waterway, features Dutch plantsman Piet Oudolf's stylish prairie-style mix of perennials and grasses as well as blossoming trees. Not yet completed is her Garden of Forgiveness, on a war-torn site in Beirut that has yielded ruins from antiquity to the Middle Ages, to be protected and embellished by pergolas and flora representing several different regions of this Mediterranean country.

[ILLUSTRATION OMITTED]

[ILLUSTRATION OMITTED]

[ILLUSTRATION OMITTED]

Ruins themselves are reminiscent of purpose-built folly gardens of the eighteenth century. In the twenty-first century, these ruins are more likely to be deserted factories or mines. In this vein, there is something pleasantly medieval about Peter Latz's planting designs for the former Thyssen Steelworks in Duisburg, Germany, that rises up with towering cranes and rotund blast furnaces that resemble castle keeps. Old bunker walls form cloister-like enclosures for low undulating hedges that create formal broderie gardens, and the rigidity and rusting patina of the structures are an evocative foil for grids of flowering trees and great swaths of plants of one colour.

The influence of Roberto Burle Marx, the eminent Brazilian landscape architect of the recent past, was evident in patterned designs that enliven urban streetscapes as a visual amenity either seen from above or experienced at ground level. As old Shanghai is disappearing into a modern high-rise city, California landscape architect Tom Leader has sought to preserve traditional materials in his Shanghai Carpet, a 650ft-long sunken pedestrian plaza in a commercial district. By collaging into abstract designs recycled stone, brick and timber from the Yellow River Gorge project, he retains the familiar textures associated with old Chinese gardens albeit in a glass and steel environment. Also in Abalos & Herreros' Northeast Coastal Park, around a municipal waste-management project on Barcelona's waterfront, oval and triangular tree-surrounds and mosaic designs recalled both Marx's biomorphic patterns along Rio boulevards as well as the decor in Antoni Gaudi's Park Guell.

[ILLUSTRATION OMITTED]

[ILLUSTRATION OMITTED]

But the phenomenon most clearly delineated by this thorough and ambitious exhibition is how cities are totally transformed by the reclamation of formerly desolate areas, the majority along waterfronts. In San Francisco, George Hargreaves' Crissy Field has reinstated tidal wetlands and a popular bayside promenade on an old US army airstrip; in Seattle, Weiss/Manfredi Architects are building the elevated zig-zag Olympic Sculpture Park on a series of green platforms including a garden pavilion over a highway and railroad line along Elliott Bay; and in New York City, Field Operations has designed Fresh Kills Lifescape, a major nature and wildlife sanctuary on the city's long-term Staten Island garbage dump that incorporates wreckage from September 11. The seductive surface beauty of these installations, both in the exhibition and on the land, belies the impressive level of knowledge and expertise about natural science and infrastructure required of landscape architects, in whose hands is obviously invested the future of our cities.

Groundswell: Constructing the Contemporary Landscape, Museum of Modern Art, New York until 16 May www.moma.org