[7] In this work, titled Alpi Marittime, Penone intervened in the growth processes of a tree, whose form retained the memory of his gesture over time.

[7] One of his acts involved the flow of the waters in a stream, the vital sap which gives strength to the tree and on which the artist draws constantly in his work, a vehicle of growth and proliferation.

In 1969, Penone's works were published in the Germano Celant's seminal publication Arte Povera in a form of a sort of diary correlated with drawing, photographs and brief notes.

In 1970, Penone created two sculptures, titled Albero di dodici metri ("Trees of Twelve Metres"), as performances during Aktionsraum 1 in Munich, Germany.

[10] Another Albero di dodici metri, dating from 1980, was shaved out of a beam to its full height, with the exception of a part at the top of the plant that used to form the base of the sculpture.

Other examples of trees, carved in different ways out of beams, make up the various installations titled Ripetere il bosco ("Repeating the Forest") at the Stedelijk Museum, Amsterdam, in 1980 and at the Castello di Rivoli Museo d'Arte Contemporanea in 1991.

Developing one's skin against the air, water, earth, rock, walls, trees, dogs, handrails, windows, roads, hair, hats, handies, wings, doors, seats, stairs, clothes, books, eyes, sheep, mushrooms, grass, skin ... " wrote the artist, reflecting on the quantity of voluntary and involuntary signs that bodies disseminate and spread on different things: the neon lights in a gallery, the panes of glass in a window at the Kunsthalle in Kassel at "Documenta 5" in 1972, on a stone in Svolgere la propria pelle/pietra ("Developing One's Own Skin/Stone") of 1971, or on the fingers in Svolgere la propria pelle/dita ("Developing One's Own Skin/Finger") of the same year.

Penone's purpose is to produce the work starting from an image as automatic and unconscious as a fingerprint, and to make it conscious and voluntary through the irreplaceable action of drawing, which enlarges it and retraces it in all its art.

The procedure adopted by the artist is articulated in different phases: making strips of adhesive tape adhere to his skin sprinkled with black, or pressure imprinting his own body or spreading a fine layer of resin on his eyelids and then photographing the image derived from the contact, projecting it enlarged onto paper or other surfaces, where it is transcribed in charcoal or pencil and with another act of contact, which the artist exerts by drawing.

[12] With these works, he reproduced the volume of the breath against his body in the form of a large clay vase, making visible a performative gesture of the artist.

[9] The artist then painstakingly carved the stone to replicate the natural processes that have shaped the rock in the river, copying the ricochets and bumps as closely as possible.

In his installation in Basel's Merian Park in 1984, he began to engraft vegetation onto his sculptures, as appears in his solo exhibition at the Marian Goodman Gallery in New York in 1985.

Sometimes the canvases are united in a single work with the trunks that produced them, or with Gesti vegetali ("Vegetation Gestures"), as in his installations in 1986 at the Museum of Grenoble in France and the Palais des Beaux-Arts in Charleroi.

Starting in 1987, Penone created large glass sculpture in the lorm of nails and places them in contact with different materials, piles of leaves, forest trees, logs and blocks of marble.

In the cycle of works titled Terre ("Lands") created starting from 1988, the earth sedimented in layers, as in its natural state, is enclosed in a transparent glass parallelepiped through which can be seen the imprint left by a gesture of the artist, the upheaval in the soil which preserves the image of the hand that caused it.

A Y-shaped transparent glass tube containing soil constitutes the central element of the sculpture and raises the subject of the relationship between man and nature.

Respirare l'ombra ("Breathing the Shadow") is a dimly lit room lined with laurel leaves, where visual and tactile impressions combine with olfactory sensations.

In another installation, shown for the first time at the Galego Contemporary Art Center at Santiago de Compostela and then at the Palais des Papes in Avignon in 2000, in the centre of one of the walls there appears a gilt bronze lung, whose lobes are also modeled using laurel leaves.

The work forms part of a series made from acacia thorns applied to silk and sometimes associated with slabs of marble, whose veiningin relief is shown to match traces marked by the vegetation.

An example is the work titled Pelle di marmo su spine d'acacia ("Marble Skin on Acacia Thorns"), exhibited in 2001 at the Musée d'Orsay of Paris and the Fujikawa Gallery in Osaka.

Bark also underlies the casts that appear in Lo spazio della scultura ("The Space of Sculpture") an installation presented at the recent exposition at the Studio per l'Arte Contemporanea Tucci Russo at Torre Pellice and the Museum Kurhaus Kleve between 2006 and 2007.

In this outdoor work, the human action, hence culture, is compared to the force of natural elements and expressed in the design of a path traced by the vegetation, whose outline represents the growth of a tree.

"[2] Since 1969 Penone has been one of the leading representatives of Arte Povera, the critical theory coined by Germano Celant in 1967 and based on the work of a number of Italian artists, including Giovanni Anselmo, Alighiero Boetti, Luciano Fabro, Jannis Kounellis, Mario Merz, Marisa Merz, Giulio Paolini, Pino Pascali, Michelangelo Pistoletto and Gilberto Zorio.