Plant of the Month: April 2021

Wood Anemone

by Peter Williams

William Robinson who pioneered the naturalistic style of gardening wrote in 1921 – “The wood anemone is so often seen in the woods that there is rarely need to grow it; but some of its varieties are essential, most beautiful being Anemone Robinsoniana…”  (The English Garden p. 108, 1921)

Fig. 1 – Anemone nemorosa ‘Robinsoniana’

This charming variety is one of many selections made from wild populations of Anemone nemorosa, one of our earliest flowering native plants.

Wood anemones grow on a wide variety of soils from acid sands to heavy basic clays and are widespread throughout the UK and Western Europe. Their range extends from Ireland in the west to Russia in the east and from northern Spain to Scandinavia. Whilst the vast majority of naturally occurring wood anemone are white, pink and blue flowered forms are sometimes found and may be locally abundant. The pale blue ‘Robinsoniana’ is thought to have occurred in an Irish woodland and introduced into the Oxford Botanic Garden in about 1870.  William Robinson became associated with the variety because he was given a rhizome segment by the curator of the garden William Baxter, and planted it in his own garden at Gravetye Manor in West Sussex and subsequently wrote enthusiastically about it.

Wood anemones are usually associated with deciduous woodlands and large colonies are indicative of ancient woodland.  This is because wood anemones are very long-lived perennials that spread slowly from underground rhizomes. Each year a mature colony may expand its edges by up to 2.5 cm if it is growing well, but a young colony may expand at twice the rate. The one in Fig. 2 that measures just over one metre in diameter, is probably between 10 and 20 years old.

Fig. 2 – Isolated colony of A. nemorosa at Castle Howard that might have started from a seed or segment of rhizome

Large sheets of wood anemones in woodlands may be made up of individual colonies that are hundreds of years old. Ecological studies have shown that whilst fertile seed is produced, very few seedlings become established. Surprisingly, however, the main agents for dispersing wood anemone seed are slugs! Wood anemones are not restricted to woodlands and grow well in open sunny habitats like upland meadows. This demonstrates that the species does not require shady conditions and indeed,dense shade inhibits flowering. In woodlands managed by coppicing (where most of the trees are cut back to ground level every 20 years or so)there is a great increase in flowering of wood anemones and other members of the ground flora in the years following thinning because of the increase in light levels.Such observations indicate that wood anemones require relatively bright conditions, at least in early spring, if they are to flower well. 

The establishment of wood anemones, both in nature and in garden situations, is often said to be slow and unpredictable. This accords with my own experiences where few of my initial introductions via dormant rhizomes became established, and of those that did, the ones planted in deep shade failed to flower.  Subsequent attempts using actively growing potted plants introduced into areas that received dappled, or some direct sunshine, fared much better.

Fig. 3 – A fine clump of wood anemones at Anne Wright’s nursery garden in Tockwith

Gardeners have always been fascinated by unusual forms of well-known plants and the naturally variable wood anemone has produced many attractive varieties. The 2018 edition of The Plant Finder lists almost 100 varieties of A. nemorosa and 50+ forms of A. ranunculoides, its European ‘cousin’ with a further listing of four varieties of the natural hybrid between the two,Anemone x lipsiensis.

Fig. 4 – Left, A. nemorosa, middle, A. x lipsiensis and right, A. ranunculoides

Variation occurs in all parts of the plant but the flowers show the greatest plasticity. The brightly coloured floral parts are not petals but sepals; petals being absent. Most wild forms have six or seven sepals but the number can range from four to very many in double forms.

Fig. 5 – Left, seven sepals in a wild population in Derbyshire and right, approximately 20 sepals in a double form

The colour ranges from white, through shades of pink to blue and purple and the intensity of colour often increases as the flower ages.  Whilst double forms are quite common amongst white flowered wood anemones, there are very few double pink or blue flowered forms.

Fig. 6 – Left, Coloured engraving of a pink flowered variety ‘Flore Rubro’ from 1861 and right, ‘Tilo’

One of my favourite varieties is ‘Evelyn Meadows‘.  This is a pink wood anemone that has a relatively high number of sepals.  The handsome pale pink flowers look particularly good against its unusually dark foliage and it is quite a strong grower.

Fig. 7 – ‘Evelyn Meadows’

  In ‘Blue Eyes,’ the bases of the inner sepals are bright blue and the colour deepens with age to create a very pleasant effect. Some forms like the beautiful ‘Vestal’ have petaloid carpels giving the appearance of fully double flowers with a golden circle of anthers. This excellent variety was introduced over a century ago by a German grower and is understandably still very popular.

Fig. 8 – Left, ‘Blue Eyes’ and right, ‘Vestal’

Anemone nemorosa ‘Bracteata Pleniflora’ has been in cultivation since the end of the 16th century. Its floral parts display a green/white variegation and in ‘Virescens,’ another old variety, the floral parts are leaf like.

Fig. 9 – Left, ‘Bracteata Pleniflora’ and right ‘Virescens’

Modern day equivalents of ‘Bracteata Pleniflora and ‘Virescens’ haveflowers composed of a complex mixture of white and green petaloid and leafy segments and are currently very popular. ‘Thekla’ is an attractive variety that was found in Germany and ‘Norway’ is another good variety of this type.

Fig. 10 – Left, ‘Thekla’ and right, ‘Norway’

One of the most sought-after wood anemones at the moment is A. nemorosa ‘Explosion’ that was discovered in a Norwegian wood. It has flowers composed of green, white and purple parts and flowers on the same plant can be dramatically different.

Fig. 11- Range of forms of Anemone nemorosa ‘Explosion’

It has been suggested that the very unusual floral features are the result of a radiation induced mutation caused by contamination from the Chernobyl disaster of 1986.

The radiation explanation has also been suggested for the creation of the variety ‘Norway’ and for the very large number of variant forms of Anemone ranunculoides that have been collected from Estonia in recent times. I am not sure how strong the evidence is for these claims,but it is an interesting and plausible story and worthy of further investigation.

Since William Robinson’s day, many more varieties of wood anemone have been selected and named and the group has become very popular with woodland gardeners.Whilst the attractiveness of many of the named varieties is undeniable, and the garden woodland areas created using them can be delightful, the sight of vast sheets of wood anemones in the wild is still difficult to match.

Peter Williams

Pictures courtesy of Peter Williams, except figs 7 & 11, Anne Wright

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