Cochineal beetles that have been crushed and mixed with linseed oil and water act as the foundation wash for several of Karen Purple’s remarkable pictures on show at the North Wall Arts Centre. Other pictures are given a foundation wash created from stinging nettles that have been soaked, boiled and pulped, then distilled and applied to the canvas.

Karen draws her inspiration from the daily walks she takes through the landscape and woodland surrounding her Oxfordshire home.

During these walks she is not just observing the countryside as it changes with the seasons, but collecting objects and natural substances which, like the nettles, can be mixed, ground boiled or pulped before being distilled into the pigments and dyes that mark her canvases.

Her canvases are not always the conventional kind. In her Sonnet 1-V she has created a medium on which to paint by weaving together linen thread and wool from Castlemilk Moorit sheep collected from a wildflower meadow.

In 2009, Karen was selected to take part in an artists’ residency project at Oxford University’s Arboretum. There she discovered a surprising vividness hidden in the earth and plant life. Ochre yellows found in the soil and purples made by mixing oak galls and iron salts were among the many new hues she found in the arboretum.

Much of the work in this exhibition has been inspired by that project.

On a shelf close to the entrance, Karen has placed a couple of old entomology boxes, which are filled with so much care with small pieces of work; it’s as if they were part of a rare collection.

One (unnamed) (above) contains small pieces of charcoal meticulously wrapped in canvas and decorated with a leaf. It’s a beautiful, thought-provoking exhibit that one longs to touch. Her large canvases contain a haunting quality as the soft natural hues she has used gently interact with each other.

Fieldwork continues at the North Wall until May 6.