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Lonicera periclymenum L., Honeysuckle

Account Summary

Native, common, locally abundant. Eurosiberian temperate.

1881; Stewart, S.A.; Co Fermanagh.

Throughout the year.

Growth form and preferred habitats

An extremely familiar, scrambling climber with deliciously sweet-scented flowers growing in sunny situations in woods, scrub and hedges, Honeysuckle can also persist in deep shade, stems creeping, spreading and rooting at intervals under gaps in woodland canopy to form large vegetative clones of effective groundcover, particularly under deciduous broadleaves, and especially successful where a deep layer of leaf litter exists (Grime et al. 1988, 2007). In these two patterns of growth, climbing or creeping, some stems can be up to 6 or 7 m long (Meldris & Bangerter 1955). Young shoots and some leaves in sheltered conditions in hedgerows or climbing on trees remain wintergreen, carrying the plant overwinter in a semi-active state (Grime et al. 1988, 2007). Leaves are sub-sessile, simple, lanceolate, entire, without stipules and in opposite pairs, each pair at right-angles to the next. New leaves open in December and January from bluish-green buds and the young leaves may be slightly downy or glabrous (Lang 1987).

The woody, much branched stems of Honeysuckle twine gracefully from left to right, and do so tightly around supporting stems (or around itself), so that it can distort young growth of woody species; as such it is most unwelcome in young tree plantations where it can be extremely damaging (Grigson 1955, 1987; Mabey 1996). In hedgerows, when stems are climbing and ± erect, vegetative reproduction is absent altogether, or severely restricted, and the plant relies on seed production for its population increase. Seed is transient in the soil seed bank, surviving for less than a year, germination taking place in spring (Grime et al. 1988, 2007; Thompson et al. 1997). However, L. periclymenum appears perfectly capable of colonising secondary woodland and new hedges, and rocky slopes, presumably through its seed being transported internally by birds. Seed of the genus Lonicera that passes through birds is known to display accelerated germination (Ridley 1930, p. 336) and seedlings are seen in gardens in abundance (Snow & Snow 1988).

L. periclymenum grows best in damp (not waterlogged) situations and it can grow on clays as well as on more free draining soils (Garrard & Streeter 1983). It can survive to produce a sparse, few-leaved, growth-form in dry or in quite dark conditions. All Lonicera spp. grow best in light, fertile soil, in a fully-exposed, sunny position (Robinson 1909) but, generally, L. periclymenum in the wild displays a bias towards less-fertile, acidic soils (Grime et al. 1988, 2007). Honeysuckle also clambers on steep cliffs, up scarps and across broken, rocky ground, including on lakeshores.

L. periclymenum successfully colonises the margins of coniferous plantations and any gaps within, indicating efficient species spread by bird-sown seed. When growing in field hedges, Honeysuckle is vulnerable to grazing pressure, and tends to be scarcer in such settings. The established strategy of the species is categorised as SC, a Stress-tolerant Competitor (Grime et al. 1988, 2007).

While Honeysuckle is most frequently found in hedges and in woodland, it occupies such a wide range of other habitats the possibility of distinct ecotypic variants arises. However, this issue has not yet been investigated in Fermanagh.

Fermanagh occurrence

In Fermanagh, L. periclymenum has been recorded in 421 tetrads, 79.7% of those in the VC. Grime et al. (1988, 2007) suggest that Honeysuckle is vulnerable to grazing pressure, though in Fermanagh and elsewhere it remains virtually omnipresent in old hedges penning cattle, sheep and horses.

Flowering reproduction

Plants in open, full sunlight flower from May to late September. There are two flowering peaks, in early June and in September. Plants in deeper levels of shade do not flower at all. The flowers, which are bisexual and irregular, are 40-50 mm long, cream flushed purplish or yellowish-pink in colour outside and creamy white within. They are widely admired and are considered one of our most exotic looking wildflowers, beloved of poets and artists (Perring & Walters 1989). The flowers are borne sub-sessile, in simple umbel clusters or whorls of 6-15, terminating the younger shoots. The calyx has five green lobes, the corolla has a long slender funnel-shaped tube and is 2-lipped, the upper lip with four lobes, the lower lip solitary. Stamens are five; style and stigma are both solitary (Sell & Murrell 2006).

The method of cross-pollination is interesting, being effected mainly (so it is claimed, although apparently seldom observed), by night-flying moths, particularly Hawkmoths, and amongst others, the silver-Y moth (Autographa gamma) (Proctor et al., 1996, p. 92). In the evening, the flower buds are erect (vertical) and the anthers burst open within them between 6 and 7 pm, the stigma becoming receptive at the same time. However, the stigma is placed higher than the anthers, so automatic self-pollination cannot normally occur. The first flowers open at 7 pm. The lower lip of the corolla separates first and the anthers then stick out, the stigma still being held by the hook-like upper corolla lip. The corolla then moves from the vertical to the horizontal and as the flowers settle into their new position, the style is released and curves down as far as the lower corolla lip and well below the anthers. As this happens, a strong, sweet, heavy perfume is released, which is only faintly detected during the daytime. Hoverflies are attracted and settle on the anthers, devouring the pollen; in doing so, they may effect pollination by alighting on the stigma. 'Long-tongued' Hawkmoths (ie with a proboscis at least 22 mm in length) are attracted by scent and colour and they search and probe inside the lower half of the corolla tube for nectar, becoming dusted with pollen as they do so (Knight 1996).

On the next evening (or the one after that), fresh flowers in the cluster are open, but in the previous day's flowers, the corolla colour has darkened to a golden yellow and the trumpet has slowly filled with nectar. Also, the stigma has changed places with the stamens whose anthers are empty, or almost so, and moths going for more nectar readily pollinate the prominent stigma with grains from other flowers adhering to their bodies. As the corolla is more generously filled with nectar by this stage, shorter-tongued insects can manage to reach it (Knight 1996). When fertilised, the corolla eventually turns a dirty orange-brown colour and gradually loses its scent altogether (Melderis & Bangerter 1955; Hutchinson 1972; Knight 1996).

Bumblebees, especially Bombus hortorum (both queens and workers) are regular visitors both day and night, since they have a proboscis that can reach the nectar. Apis Honeybees, other Bombus Bumble bees and Hoverflies also visit the flowers both during the day and at dusk, but they are after protein-rich pollen rather than nectar. The base of the corolla tube may be holed by Bombus lucorum and B. terrestris Bumble bees, stealing the nectar and leaving an opening that can be exploited by other short-tongued insects, but this appears to be a relatively rare event (Knight 1996). If insect visitors fail to pollinate them, the flowers may self-pollinate (Knuth 1906).

Berries, 8 mm diameter, dark red, globose and stalkless in tight clusters, are ripe from mid- to late-August onwards, and a number of bird species, particularly Blackbirds, but also Song Thrush and Robin, have been recorded eating the sticky, juicy, fruits (Butcher 1961; Lang 1987; Snow & Snow 1988). However, the timing of Honeysuckle fruit availability coincides with a glut in fruit production by Rowan and other berry and drupe producing species, with the result that L. periclymenum fruits are frequently ignored by birds until later in the autumn, some fruit remaining on the plant until October or even early November. Birds transport the five or six, yellow, ellipsoid, finely netted seeds, each 4.0 × 2.5 mm, that each berry contains (Lang 1987). Bullfinch, Blue Tit and Marsh Tit are known seed predators of Honeysuckle, Bullfinch being by far the most significant of the three and the Blue Tits feeding on seeds in dried up fruits only late in the season (Snow & Snow 1988).

Variation

The Royal Horticultural Society Index of garden plants lists at least twelve distinct named cultivars (Griffiths 1994). They differ in flower colour and time of flowering, one of them cv. 'Serotina', continuing to flower well into autumn so it is referred to as the 'Late Dutch Honeysuckle' (Robinson 1909).

Fossil record

The fossil pollen record shows L. periclymenum present throughout all four stages of the Hoxnian interglacial, and the genus (almost certainly all the records being of this particular species), in the Ipswichian interglacial. However, there are no records of either the genus or this species in any glacial stage. L. periclymenum pollen is again recorded in zones VI, VIIa & VIIb of the present Flandrian interglacial, an expansion that more probably is attributable to increasing climatic warmth, rather than vegetation clearances carried out by early farmers (Godwin 1975).

Toxicity

Like other members of the Caprifoliaceae, Honeysuckle contains toxins such as saponins, valerianic acid and xylostein which can cause both vomiting and diarrhoea. The berries are of low toxicity, however, and a large intake, around 30 or more, would be required to induce gastric upset in humans. Since the berries taste rather bitter, few individuals would consume sufficient to suffer ill effects (Cooper & Johnson 1998).

British and Irish occurrence

L. periclymenum is common, widespread and locally abundant throughout the whole of B & I, sometimes, indeed, described as 'ubiquitous'! It reaches its highest altitude of 610 m in both Westmorland (VC 69) and Co Down (H38) (Garrard & Streeter 1983; G.T.D. Wilmore, in: Preston et al. 2002).

European and world occurrence

Common in W, C & S Europe and also in N & C Morocco (Clapham et al. 1987). However, although it is common in Denmark, L. periclymenum is restricted in Scandinavia to the W coastal fringes of Norway and Sweden south of 63oN, which accords with Hultén's classification of the species as European-Atlantic (Godwin 1975). Hultén & Fries (1986, Map 1730) regard L. periclymenum as largely restricted to W Europe north to 63oN in Scandinavia, but the plant in southern Europe and around the Mediterranean, they recognise as a separate species, L. etrusca Santi.

Names

The genus name 'Lonicera' is named in memory of Adam Lonitzer (or Lonicer) (1528-86), a German physician and botanical author of a famous herbal (Kreuterbuch) many times reprinted between 1557 and 1783 (Johnson & Smith 1946; Gilbert-Carter 1964; Stearn 1992). The Latin specific epithet 'periclymenum' is from the Greek 'perikleia', meaning 'I entwine' or 'to entwine around' (Johnson & Smith 1946). Another suggestion is that 'periclymenum' or 'periklymenon' was a Greek name that Dioscorides gave to some twining plant, probably a Honeysuckle, and thought by some to be Lonicera etrusca (Gilbert-Carter 1964; Gledhill 1985; Stearn 1992).

The English common names 'Honeysuckle' and 'Woodbine' are often applied to this plant. Honeysuckle is 16th century in origin, from the Old English 'honigsūge', from 'sūgan' meaning 'to suck', derived from the pleasing experience of sucking the nectar from the flower tube (Grigson 1974). 'Woodbine' is derived from the Old English 'wudu-binde', meaning 'wood binder', from the twining woody stems (Grigson 1974). Honeysuckle was one of the plants that averted the evil powers abroad on May Day, and by magic spells, took care of milk, butter and cows (Grigson 1955, 1987). The latter author lists as many as 26 variant English common names for the species, many referring to the twining, binding capabilities of the woody stems (eg 'Bearbind', 'Bind', 'Bindwood', 'Woodbind'), or the sweet taste of the sucked nectar (eg 'Honey bind', 'Honeysuck', 'Suckles', 'Suckle-bush', 'Sucklings' and 'Sweet Suckle'.

Threats

None.

References

Grime, J.P., Hodgson, J.G. and Hunt, R. (1988, 2007); Mabey, R. (1996); Lang, D.C. (1987); Cooper, M.R and Johnson, A.W. (1998); Knight 1996; Knuth 1906; Melderis & Bangerter 1955; Hutchinson 1972; Proctor et al., 1996; Grigson 1955, 1987; Grigson 1974; Gilbert-Carter 1964; Gledhill 1985; Stearn 1992; Johnson & Smith 1946; Griffiths 1994; Ridley 1930; Snow & Snow 1988; Hultén & Fries 1986; Godwin 1975; Clapham et al. 1987; Preston et al. 2002; Griffiths 1994; Butcher 1961; Thompson et al. 1997; Sell & Murrell 2006; Robinson 1909; Garrard & Streeter 1983; Perring & Walters 1989.