Acaena inermis Purpurea

The Acaena inermis 'Pupurea' is a very pretty form with richly coloured foliage of a robust and hardy New Zealand burr. This small perennial plant forms a superb evergreen ground cover whose colour evolves from pink to purple-violet and brick red, with its small finely cut leaves sometimes tinged with olive green shades in winter. Its discreet summer flowering is followed by an original fruiting, in the form of spiky globules. This plant beautifully cascades from stone walls and decorates alpine rockeries, troughs, and sunny borders with a pretty purplish moss. While this burr appreciates well-drained soils, even dry in winter, it requires some coolness in summer.

The Acaena inermis is a rhizomatous plant native to New Zealand, belonging to the Rose family. It is a relative of the burnet plant, which is shown by their similar foliage. The 'Purpurea' form slowly forms a dense mat, 10 cm (4in) high, which in theory can spread without limit. Its foliage is remarkable; compound and finely cut into dentate leaflets not exceeding 7 mm (1in) in diameter, it displays changing colours, even more vibrant with intense sunlight. It is generally evergreen. Its leaves are carried by underground and root-running stems, allowing them to spread over time. In June-July, short stems bear rather inconspicuous small flower heads. They consist of tiny flowers in the form of small green-brown spheres. In autumn, the mat is adorned with curious small globular and spiky fruits, similar to tiny chestnuts. This lovely plant is not invasive, and its growth is easily controllable. All that is needed is to remove rooted stems and compost them or plant them in another part of the garden.

The 'Purpurea' Acaena thrives in almost all well-drained soils, in an alpine climate, but it is generally much less demanding to grow than strictly mountain species. On the other hand, it does not tolerate very dry summers at all. Perfectly hardy, this elegant ground cover is ideal in rockeries, at the edge of flower beds, above stone walls or to cover the base of bushes, in the company of the very romantic Kenilworth ivy (Cymbalaria muralis). Acaena pairs well with small spring bulbs and colourful grasses such as Red Baron Japanese blood grass (Imperata cylindrica). It is easily cultivated in tubs or containers where it will elegantly spill over. Pairing well with small sedums, houseleeks, saxifrages, or small grasses, acaena can also be used on a green roof or vertical garden wall, in cool climates though.