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Anemone nemorosa L., Wood Anemone

Account Summary

Native, common, widespread and locally abundant. Eurosiberian temperate.

8 April 1862; Smith, T.O.; near Ardunshin.

March to November.

Growth form and preferred habitats

One of the prettiest if not the earliest of the welcome harbingers of spring in its typical habitat of deciduous woods and hedges, A. nemorosa is a perennial geophyte with a shallow, brittle, slender, brown rhizome which branches and forms clonal patches up to 5 m in diameter (Shirreffs 1985). As with other vernal species, A. nemorosa is really a shade-avoiding rather than a shade-tolerant species since it exploits the light phase in woods, scrub and hedges before the leaf canopy develops. While it tolerates a wide variety of soils, as a rule A. nemorosa is best developed on soils that are moist to wet in spring. Such soils are often of relatively heavy texture or rich in humus, ie between 7% and 20% organic matter (Grime et al. 1988), or even more than this in Fermanagh.

The very superficial root system of A. nemorosa runs at a depth of just 5-10 cm, a feature which exposes the plant to early season drought but which allows it to survive in much wetter soils than its common competitor, Hyacinthoides non-scripta (Bluebell), the bulbs of which are drawn down year-by-year by contractile roots, often reaching depths of 15-25 cm where they may easily suffer waterlogging (Grabham & Packham 1983). While this is the case, A. nemorosa is not really a wetland species, it can merely tolerate moist soils on the fringes of marsh, fen and bog, although in some of these situations it may have to endure periods of submergence.

While Wood Anemone appears to prefer less fertile limestone woodland soils, it is not in any way confined to them, but rather it may be expected in any shady situation including low growing ericaceous heath. It does not, however, penetrate peat bogs where the soil pH falls below 3.5, which appears to totally exclude the species (Shirreffs 1985; Grime et al. 1988).

In hedges, limestone pavement and long-established grassland, the presence of A. nemorosa can frequently be associated with previous scrub or woodland cover, so that the plants are seen as remnants of previous vegetation. When found on cliffs, however, or in sheltered spots above the tree-line, there can be no question of relict status, and one wonders exactly how the species was transported to these elevated sites. Then the plant typically occurs in rock clefts, or on sheltered, often north-facing ledges, or shaded by overhanging sub-shrubs or trailing vegetation, all conditions providing the shelter, shade and high humidity the species requires.

Fermanagh occurrence

Locally, the species is very common and widespread, especially in lowland Fermanagh, having being found in 290 tetrads, 54.9% of those in the VC. The most typical habitats it occupies are deciduous woods, hedgerows and river banks but, in the prevailing wet conditions of Fermanagh, A. nemorosa is capable of extending into grassland and other open habitats, including more rarely, cliff ledges and scree on the talus slopes beneath cliffs.

British and Irish occurrence

Wood Anemone is common and widespread throughout Britain and Ireland, although absent from Orkney and Shetland and rare in areas like the English Fens and other exposed situations where woodland (and indeed anything approaching dry land) are sometimes scarce. The previous dearth of records from the Republic of Ireland, which was regarded as probably under-recording (Shirreffs 1985), was remedied to a considerable extent in the New Atlas survey. The distribution remains fairly patchy in the Republic, except in parts of the far south and in the Dublin and Wicklow area, where there are more resident plant recorders (New Atlas). However, one must never overlook or underestimate the likely limiting ecological factor(s), and local excesses of soils, exposure and wetness must certainly also restrict distribution.

Phenology and growth

The shoot emerges from below ground in March, pushing up through the leaf litter crozier-like, with three folded leaf-like bracts surrounding and protecting the solitary flower bud. The shoot soon straightens, the palmately cut bracts unfurl and expand, and the flower stalk elongates carrying the flower well above the ring of three involucral bracts. The flower bud then loses its green tinge and, since the perianth in this species consists of just one set of leaf-like segments, the tepals or petal-like sepals expand (plant anatomists tell us they are not true petals), and the first anemone flower opens 'for business'. This usually occurs around the end of March or the beginning of April depending on season, habitat and geographical location (Shirreffs 1985). The true leaves are very similar in appearance to the bracts, but they are produced a short distance further along the rhizome from the flower-stalk and they do not appear until after the flowers have opened (Step & Blakelock 1963).

Growth rates in A. nemorosa are extremely low: seedlings take at least five years to form a viable rhizome, plus perhaps another five to ten years for the plant to become capable of flowering. The average annual extension in adult plant rhizomes is only 2.5 cm, so vegetative spread is also extremely slow (Ernst 1983; Shirreffs 1985). By June, the sexual reproductive cycle has been completed, and in the shaded floor vegetation the plant rapidly dies down and disappears completely below ground by around the middle to end of July.

Flower variation and pollination

All parts of the anemone plant are very variable (ie phenotypically plastic), and this is particularly true of the flower. Flower stems vary in height between 10-30 cm above ground (with a mean of 14 cm), each bearing a solitary blossom 10-40 mm in diameter. The perianth is composed of from 4-11 elliptic sepals (most frequently six or seven). The sepals are usually white inside, purple tinged or streaked outside, but purple, blue and pink forms also occur, the former sometimes quite frequently (Shirreffs 1985). Stamens are numerous, usually about 45 in three ranks of differing filament length, and as Wood Anemone flowers offer no nectar, unspecialised insects visit them to collect the openly presented protein-rich pollen as food for themselves and their brood. The insects attracted by the perianth's appearance, movement and food reward range from honey-, bumble- and solitary-bees, to beetles, flies, thrips and bugs (Proctor & Yeo 1973).

When the flower first opens the maturing stamens are crowded over the stigmas and prevent them from being pollinated, though pollen is already being shed from the ripe, outer anthers at this stage. After about a week, the rest of stamens ripen and diverge, and during the second week the white, translucent stigmas can be pollinated. Self-fertilisation is prevented by an incompatibility mechanism, making cross-pollination obligatory (Proctor & Yeo 1973). The flowers are held erect during the day and move in the slightest breeze, but they droop and fold at night, or in dull or wet weather. The stigmas shrivel and blacken after pollination and a crowded head of single-seeded achene fruits then develops.

Reproductive biology

The number of carpels in the flower varies from 9-42, with a mean of 22 (Salisbury 1942). Shirreffs (1985) found the mean number of carpels ranged from 16 to 31 at different sites, the lower figures being associated with non-woodland sites, such as open grassland. Flowering density is greatest in woodlands since this is where the species forms dominant carpets. The mean number of fruiting flowers in a typical A. nemorosa carpet is around 152/m² (Salisbury 1942), with higher figures in coppice (380 flowers/m²), but much lower figures than this are found in densely shaded areas.

The cluster of achenes breaks up and the individual fruits are shed from May to June, depending on the local climatic and micro-climatic conditions. When shed, the achenes of A. nemorosa contain an immature embryo that requires a moist, cold, after-ripening period lasting from 4 to 6 months before they ripen sufficiently and become capable of germination (Vegis 1961). Germination occurs in the following spring, but the typical rates that occur in the wild are poor. Ernst (1983), however, found somewhat improved figures of between 5% and 35% germination occurred after long, cold winters in Germany, with lesser figures being obtained after mild winters. This indicates that seedling recruitment into the existing mature population is irregular. Ernst concluded that recruitment of seedlings and young plants (ie 2nd to 5th year classes) in the study area was inadequate to maintain a viable long-term population. The mortality of the young plants was very high in the first and second years (88.2% ± 13.5%), which is comparable to that shown by other, bulbous vernal species, namely Allium ursinum (Ramsons) (Ernst 1979) and Narcissus pseudonarcissus (Daffodil) (Barkham 1980).

In his study, Ernst (1983) calculated that A. nemorosa generally does not invest more than 5% of its biomass resources into sexual reproduction, while most of the fixed energy (production) is used to maintain the rhizome at 40 to 50 % of the total plant biomass. The annual increase of the rhizome can be as much as 150 mg. Rhizomes older than 15 to 25 years are brittle and readily separate from the parent plant. This fragmentation constitutes a rather unspecialised form of vegetative reproduction and, in the sites studied, it appears to be the main mechanism maintaining the population.

Population persistence

Wood Anemone showed a remarkable degree of persistence in neglected coppice uncut for 30 to 40 years in E England, being present in 70% of plots in five such woods. This figure was surpassed only by Rubus fruticosa (Bramble) which had a 100% occurrence (Brown & Oosterhuis 1981). It is interesting that during the same study, germination tests carried on for two years with soil samples taken from the upper 15 cm of the profile (after litter removal), found no seedlings of A. nemorosa present, nor indeed any seedlings of Hyacinthoides non-scripta (Bluebell) or Mercurialis perennis (Dog's Mercury), although all three of these often dominant carpet-forming woodland species had survived in at least 50% of the neglected, overgrown woodland coppice investigated. This agrees with the general finding that species of shaded habitats tend to lack mechanisms for widespread and rapid seed dispersal (Webb 1966; Brown & Oosterhuis 1981): the seeds of such species are heavy, seed production is relatively low (Salisbury 1942) and they are in the main dispersed by rainwash, in clinging mud, or by ants (Ridley 1930).

Possible dispersal mechanisms

Anemone nemorosa has no specialised means of achene dispersal, although it has been suggested that ants may be involved (Ridley 1930; Oberdorfer 1970). The achene has no attached food body, so that ants and other animals are unlikely to show any interest in them. However, if ant dispersal (ie myrmechory) really is the sole, or even the principal method of seed dispersal, then the efficiency and efficacy of the process must be rather severely limited since Ernst (1983) found the distance between parent plants and established seedlings was never more than 13 cm. Brown & Oosterhuis (1981) observed that even a relatively narrow strip of non-woodland habitat around 50-100 m wide, would create an ecological hurdle that most plant species of shaded habitats could hardly ever cross. The apparent lack of an effective seed dispersal mechanism in A. nemorosa, together with the exceedingly slow diffusive spread of the rather long-lived, creeping rhizome, results in the observed single species carpet of intermingling clones of the plant which we see mainly in the relative stability of woodland or undisturbed scrub vegetation.

Competing woodland species

The carpet growth of A. nemorosa enables it to shade out many smaller competing species, allowing it to become dominant at sites which are wet in the spring. However, it is usually unable to compete with taller growing vernal species, including for instance Hyacinthoides non-scripta (Bluebell), Allium ursinum (Ramsons) and, in Britain, but not in Ireland, Mercurialis perennis (Dog's Mercury). In these instances, A. nemorosa is either completely ousted by the shade of the taller plants and their competition for other limited environmental resources, or it survives in smaller numbers only as a subsidiary companion species (Shirreffs 1985). However, where there is a considerable degree of woodland disturbance (eg grazing, trampling or coppicing), A. nemorosa is often better able to withstand these external pressures than can Bluebells, Ramsons or Dog's Mercury, especially where such disturbance is combined with seasonally wet soils (Grime et al. 1988).

Toxins

A. nemorosa has some degree of protection from grazing animals since it contains the volatile, oily, irritant substance, protoanemonin, the concentration of which reaches its peak when the plant is flowering and most conspicuous. The toxin has an acrid taste and causes burning in the mouth and throat, effectively deterring animals from eating much of it (Cooper & Johnston 1998). This said, a study in Warwickshire woods made 50 years ago, when rabbit populations were very much more active than now, found a number of widespread woodland herbs, including A. nemorosa, suffered heavy grazing pressure near warrens, sometimes almost to vanishing point (Knight 1964). Several fungi, both Ascomycete and Basidiomycete, attack A. nemorosa leaves and rhizomes and can suppress flowering partially or completely (Ernst 1983; Shirreffs 1985).

Fossil record

Fossil pollen of Anemone-type has been found in Scotland from the late-Glacial period (13,000-10,000 BP), but it is not specifically that of Anemone nemorosa, but could also come from the related species Actaea spicata (Baneberry) or Pulsatilla vulgaris (Pasqueflower) (Shirreffs 1985).

World occurrence

Beyond the British Isles, A. nemorosa occurs throughout the suboceanic northern temperate zone of both Europe and W Asia and reaches 67° N, just within the Arctic Circle in Norway (Shirreffs 1985; Hultén & Fries 1986, Map 827; Jalas & Suominen 1989, Map 1630; Jonsell et al. 2001). Forms of A. nemorosa are widely grown in gardens within and beyond the natural range of the species. Griffiths (1994) lists 19 garden cultivars of the species and Jonsell et al. (2001) mention an additional yellow form cultivated in Sweden.

Herbal use

A. nemorosa has entirely fallen out of use in herbal medicine today, although the older herbalists such as Gerard and Culpepper listed numerous ailments it was supposed to alleviate, eg headache, rheumatic gout, lethargy and for cleansing ulcers (Grieve 1931). As the plant is decidedly poisonous, the modern advice is to BEWARE of any such remedies.

Names

The name 'Anemone' is often said to be derived from Greek 'anemos', wind, plus the feminine patronymic suffix, making it 'daughter of the wind' (Gilbert-Carter 1964). The connection with the wind is somewhat obscure in this particular species, however, although the flower does dangle and flutter in the breeze if it is strong enough, so perhaps the alternative explanation may fit better. This suggests the name is a corrupted Greek loan word of Semitic origin, referring to the lament for slain Adonis, or Naaman, whose shed blood produced the blood-red flowers of Anemone coronaria (Crown Anemone), or Adonis annua (Pheasant's Eye), both common spring species in the Mediterranean region (Gilbert-Carter 1964; Stearn 1992). The Latin specific epithet 'nemorosa' means, 'growing in woods' or 'in shady groves' (Gledhill 1985).

There are dozens of English common names listed in Grigson (1987), the two most frequently used being 'Nemony' or 'Neminies', a simple contraction of Anemones, and 'Wind-flower'. Both of these names are borrowed from Anemone coronaria, famous in Greek legend as mentioned above. Other names include 'Wood Crowfoot', 'Moonflower', 'Cowslip' (the latter rather odd), and two names that refer to an odour, 'Smell Foxes' and 'Smell Smock', both of which might be derived from the sharp, unpleasant taste and the faint smell of A. nemorosa (Grigson 1987).

Threats

Anemone nemerosa regenerates mainly by rhizome growth and while large clones do develop and genets can persist for a long number of years, seed persistence is low, dispersal is very poor and seedling establishment is extremely slow. Thus the plant is a poor colonist of new sites and Grime et al. (1988) believe it is decreasing in England in grassland habitats at least, and perhaps also in some woodlands. Certainly it is not equipped for jump-dispersal and the colonisation of new habitats, so it may well be a relict in many of its existing sites.