Landscape with Tree is divided by linear horizontal divisions into four consecutive bands of uniform colour. The tree is rooted in the foreground of dark purple. It rises through a narrow strip of lighter purple and the precipitous mountain-like form of earth green, which looms in the background. The summit of the mountain is illuminated by an outline of bright blue. The sky is midnight blue and fades to a darker hue towards the top edge of the canvas. Notwithstanding the pictorial recession created by these consecutive bands of colour, the painting has a shallow depth of field owing to the thinness of the medium and the consequent prominence of the canvas texture. The setting is almost certainly Holy Island viewed from the Isle of Arran in Scotland. Craigie Aitchison spent childhood holidays there but first returned as an adult in 1970, shortly after the unexpected death of his mother. His visit was prompted by the office of scattering her ashes near Goatfell overlooking Holy Island. For Aitchison, the landscape was charged with unspoken memories and strong emotion. Shortly before he painted Landscape with Tree, he depicted Holy Island for the first time in a work entitled The Island. Thereafter many of his landscape paintings included the familiar wide horizon and consecutive bands of land, sea, island and sky. Andrew Gibbon Williams suggested that Aitchison treated Holy Island and Goatfell as ‘vehicles for expressing his innate melancholy on a grander scale.’

A defining characteristic of Aitchison’s painterly style was a combination of thin, untextured paint and glowing colour. His mature paintings typically possess considerable depth and intensity of colour that was attained by applying fine washes of oil paint thinned down with turpentine. Instead of drawing the outlines of his subject onto the canvas, he proceeded by advancing an area of colour outwards until it reached the necessary frontier. This method and the imagery of his paintings have been described by Aitchison’s friend and one-time sitter Patrick Kinmonth:

[…] they’ve been discovered, edge to edge. They haven’t been outlined and filled in. And that was his process. It was very tentative and involved a great deal of rubbing out. And he often said, “it’s only when I rub something out that I find what I mean underneath.”

In Landscape with Tree, it is characteristic of Aitchison’s method that the linear divisions in the landscape are not precisely parallel or perpendicular to the edges of the canvas. Instead they have a tremulous, hand-drawn quality that enlivens the areas of colour which they delimit.

In Landscape with Tree, a diagonal streak of warm colour breaks across the island mountain and suggests a ray of light. Intermingled with the light are two flower-like forms of blue and white, each with yellow seedheads. From the early sixties Aitchison occasionally included rays of light as indications of some soulful, divine exchange or transmission. The artist’s Bedlington terriers Sugarbush, Wayney and Sleepyhead died in 1982, 1986 and 1999, and he commemorated these events by painting lamentations in which a bar of bright colour suggests a transmission from earth to heaven. From this it seems Aitchison believed that animals have souls. In the case of Sugarbush Dead, the animal is set against the background of Holy Island. Sugarbush in the foreground is connected with the sky by a strong diagonal ray of brilliant colour, which jumps forward against the otherwise low-key colouring. In many of Aitchison’s crucifixions, the figure of Christ emits a straight beam of light that connects him to the top edge of the canvas, which might suggest a soul departing for heaven. In one of the earliest examples of this, Crucifixion (1964), the painting shows Christ flanked by angels with a diagonal beam of pale yellow connecting his head with the top of the picture. In some crucifixion paintings, the ray of light does not reach the figure of Christ, and it seems as if the emission is coming down to earth rather than shooting outwards from the figure. It is possible that Landscape with Tree also represented for the artist some undefined spiritual transition or transformation, perhaps relating to the recent death of his beloved mother.