Acaena

About 60 species of Acaena occur in nature, distributed primarily in the Southern Hemisphere, especially in New Zealand, Australia, Tasmania, the Andes, Mexico and South America.

These are mat-forming shrubs or subshrubs 10 to 30 cm high, with woodying shoots and overwintering leaves. Numerous, very branched shoots interweave to form a very dense groundcover. Acaena leaves are pinnate, 6–10 cm long, with very small leaflets. Tiny flowers are grouped into small inflorescences (8–10 mm in diameter), resembling little balls with thin soft spines sticking out in all directions and raised above the foliage on leafless stems to a height of 15 to 30 cm. Acaena bloom from mid-summer to late autumn.

Acaena appeared in cultivation with us relatively recently but quickly began to gain ground. It is undemanding and easy to grow. By spreading, it forms attractive carpets thanks to the prostrate stems, which root where they touch the soil. Stem leaves are alternate and do not fall in autumn.

Acaena argentea — Acaena argentea Ruiz & Pav. = Ancistrum argenteum (Ruiz & Pav.) Kunth

Native range - South America; found in Peru and Chile in the alpine zone of the Andes. Grows at altitudes of 1000-4500 m.

Perennial 1-5 cm high. This species tolerates environmental change poorly. It is attractive for its bluish-silver leathery leaves 4-6 cm long composed of 4-6 leaflets that lie close to the prostrate stems. This species is characterized by pubescence on the underside of the leaves. The upper surface of the leaf is glabrous. Leaves are very small, up to 3 cm long, with a strong metallic sheen. Flowers in May-June. Seeds form in July-August. Has the variety Acaena argentea var. gracilis Hieron = Acaena subincisa Wedd.

Acaena buchananii — Acaena buchananii Hook.f.

Native range - New Zealand. Hardiness zone: 6.

Plant up to 5 cm high with silvery-gray, slightly pubescent leaves. It has thin, very branched shoots up to 60 cm long. Lateral shoots are short, 10–25 cm. Leaves are concentrated at the shoot tips. Heads are attractive with yellow spines. The plant forms low dense mats up to 10 cm high. Flowers in June. Seeds form in July-August. Requires well-drained soil. Tolerant of calcareous soils. Relatively resistant to trampling.

Acaena inermis — Acaena inermis Hook.f.

Native range - New Zealand, where it grows on the mountain meadows of the South Island.

Perennial 5-10 cm high. Leaves reddish. Small flowers with green sepals and white stamens appear in summer. Requires a sunny position with humus-rich, well-drained soil. Seeds are sown in winter. Seedlings appear over 3-12 months at 16-20 °C.

Acaena microphylla — Acaena microphylla Hook.f.

Native range - New Zealand. Not very frost-hardy. Hardiness zones: 6-8.

One of the most common in gardens. A plant with solitary rounded brownish-green leaves with finely toothed margins. Its not very long shoots (maximum length 60–65 cm) are highly branched, intertwining to form a very dense sward 5–7 cm high, resembling a lawn. Leaves withstand being under the snow without damage. Small flowers are grouped into spherical inflorescences on thin flower stalks about 5 cm long. Fruiting specimens are especially attractive. Their inflorescences turn into a dark brown head about 1 cm in diameter, studded with long bristles. Flowers in July-September. Bristly seed heads appear in August. In spring, isolated patches of decay may occur, which by the end of April recover quickly.

Acaena splendens — Acaena splendens Hook. & Arn.

Perennial 10-20 cm high. Leaves composed of 3-5 pairs of oval-lanceolate silvery leaflets with toothed tips. Flowers on tall scapes with purple anthers appear in summer. Forms dense mats.

Location: Acaena grows in sunny positions and in partial shade; however, in partial shade the plants grow taller than usual and the mat becomes loose.

Soil: Acaena requires humus-rich, not very heavy, well-drained garden soil. It does not like waterlogged or excessively dry sites. Excess moisture adversely affects the plant's winter survival.

Care: in winter acaena suffer not so much from low temperatures (they are protected under a layer of snow) as from dampness during snowmelt. If snow does not lie on the ground for a long time, it is better to cover acaena with a single layer of brushwood or conifer boughs.

Propagation: acaena are easily propagated by seed. Sow them in spring. A week of stratification promotes more uniform germination. Seedlings appear relatively quickly, are pricked out, and by the end of summer form small plants capable of overwintering under snow. But it is easier to propagate acaena by stem cuttings. Lifting an acaena runner you will find aerial roots at the nodes of last year's shoots. A cutting must be taken with a segment of the previous year's shoot, only on it do roots form actively. In late spring to early summer, when acaena shows active shoot growth, cut 12–15 cm long cuttings. For successful rooting the cuttings require regular misting.