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Sambucus nigra L.

2002; Wiley; Volume: 90; Issue: 5 Linguagem: Inglês

10.1046/j.1365-2745.2002.00698.x

1365-2745

M. D. Atkinson, Elaine Atkinson,

Plant Physiology and Cultivation Studies

Deciduous shrub or more rarely a small tree to 10 m, often with straight, vigorous erect shoots from the base; branches often arching. Bark brownish-grey, deeply furrowed, corky. Branches containing a white, porous pith. Twigs stout, greyish, with prominent lenticels. Leaves pinnate; leaflets 3–(5–7)−9, 3–9 cm, ovate, ovate–lanceolate or ovate–elliptic; acuminate; serrate; sparingly hairy on veins beneath. Lower pair of leaflets with short stalk (4–5 mm), other leaflets sessile. Petiole 3–4 cm, deeply grooved on the adaxial surface; stipules 0 or very small and subulate. Axillary buds triangular, reddish, 2–3 mm. Foliage and young shoots foetid. Stalk-like extrafloral nectaries (5–10 mm × 1 mm) occur at the base of leaves and leaflets. Inflorescence flat-topped, 10–20 cm diameter, corymbose with 5 primary rays. Flowers 5-merous, actinomorphic; calyx limb very small; corolla rotate with short tube and flat spreading limb; 5 mm diameter, cream-white; fragrant. Anthers extrorse, cream. Style short, with 3–5 stigmas. Fruit a drupe, 6–8 mm, globose, black, rarely greenish, containing 3–5 compressed seeds (for seed sizes and weights, see section VIII(C)). Pollen grains pale yellow, ellipsoidal, densely tuberculated, 31 × 15–16 µm (Knuth Poll. II). Sambucus (Caprifoliaceae) is a genus of approximately 20 temperate and subtropical species of small trees, shrubs and herbs (Mabberley 1997). Bolli (1994) recognizes only nine, regarding S. maderensis Lowe, S. canadensis L., S. palmensis Link, S. cerulea Raf. and S. peruviana Humboldt as subspecies of S. nigra. A large number of variants are known in horticulture (Bean 1951). Two forms have repeatedly been recorded as naturalized in Britain. The green-berried form viridis, also known as fructo-albo, leucocarpa and chlorocarpa, has been seen by the authors on Fleam Dyke, Cambridgeshire, in 1985 and again in 2001 and was recorded near Sheffield by Ardron & Rotherham (1984). A variety with deeply dissected leaflets (var. laciniata) is noted in a number of local floras (e.g. Wolley-Dod 1937; Lousley 1976). The inheritance of the finely divided leaf character in Sambucus nigra was shown to be governed by a single recessive gene by Tobutt (1992). A similar genetic basis was found for the finely divided leaves of Sambucus canadensis (var. acutiloba) (Way 1965). Crosses were made among 'Aurea', 'Guincho Purple' and 'Laciniata' varieties and between two first-generation selections of S. nigra. Segregations showed that dominant genes were responsible for red and yellow leaf colour (Tobutt 1992). Elderberries are grown on a commercial scale in Denmark as a colourant in juices and home wine kits (Kaack 1990). The selection of four new varieties of S. nigra on the basis of bush yield, anthocyanin content, number of upright shoots and flavour was described by Kaack (1989). Sambucus nigra is native and widespread in the British Isles and continental Europe. It is predominantly a shrub of open areas and woodland edges and is associated with eutrophic and disturbed soils. Sambucus nigra is found throughout the British Isles except in parts of northern Scotland (Fig. 1). It does, however, grow in Shetland as an outcast on rubbish tips, and as a garden plant (Scott & Palmer 1987). It also grows in Orkney, on cultivated ground (Bullard 1995). The altitudinal limit given in Fl. Br. Isl. is 460 m. However, Halliday (1997) gives the limit in Cumbria as 470 m. Other regional limits (Alt. Range Br. Pl.) are: 380 m in W. Yorkshire, 410 m in Swaledale (N. Yorkshire) and the Forest of Clun (Shropshire), 440 m on Tal-y-Fan (N. Wales), 310 m in Kerry (W. Ireland) and 350 m in Co. Dublin. The distribution of Sambucus nigra in the British Isles. Native: (○) pre-1950; (•) 1950 onwards; introduced: (×) pre-1950, (+) 1950 onwards. Each dot represents at least one record in a 10-km square of the National Grid. Mapped by H. R. Arnold, Centre for Ecology and Hydrology, Monks Wood, using A. Morton's DMAP program, mainly from records made by members of the Botanical Society of the British Isles. Sambucus nigra occurs throughout western Europe (Fig. 2). Isolated populations occur as far north as 63° N latitude in western Norway (Atl. N.W. Eur.; Godw. Hist.; Lid 1979; Hultén & Fries 1986) and as far as 61° N in Sweden (Atl. N.W. Eur.; Lid 1979; Hultén & Fries 1986). It is not now considered native in Norway but has probably been cultivated since the Middle Ages and was well established by the 1870s (Fremstad & Elven 1999). Continuous populations are restricted to the southern coast of Norway and the western coast of Sweden (Vergl. Chor. III). East of Lithuania, the northern limit is approximately 55° N. The native distribution of Sambucus nigra in Europe. Compiled from maps in Vergl. Chor. III, Hultén & Fries (1986) and Atl. N.W. Eur. The dark shaded areas represent its continuous distribution. Isolated populations are enclosed within the light shaded regions. The precise limit of S. nigra in southern Europe differs between the maps of Vergl. Chor. III and Hultén & Fries (1986). The populations in the Atlas Mountains of Morocco, Algeria and Tunisia are thought to be introduced as well as that in the Azores (Vergl. Chor. III). Sambucus nigra is present in the northern and western part of the Iberian peninsula, in Sicily and mainland Greece but is absent from Crete. It occurs sporadically in western and eastern Turkey, particularly in the northern coastal strip. The eastern limit of its distribution is approximately 55° E. In mountainous regions, S. nigra is absent from the higher altitudes, such as above 1500 m in the Alps, 900 m in the Tatra mountains and 2200 m in Morocco (Vergl. Chor. III). It is classified as European Temperate by Preston & Hill (1997). Sambucus nigra has been introduced into various parts of the world including E. Asia, N. America, New Zealand and the southern part of Australia (Hultén & Fries 1986). The distribution limit of Sambucus nigra in north-eastern Scotland, the Southern Uplands of Scotland and Upper Teesdale corresponds to a mean October temperature below 7.2 °C (Lennon & Turner 1995). The northern limit of S. nigra in Scandinavia, and the eastern limit in Europe, also correspond to approximately this temperature (Leemans & Cramer 1991). A limit related to low October temperatures may indicate that the seeds are unable to mature during the shorter growing season at these high latitudes and altitudes. This is supported by the fact that S. nigra does not set seed in Orkney (Bullard 1979) where it grows only where cultivated. The southern limit in Europe and North Africa corresponds approximately to a mean October temperature of 15 °C (Leemans & Cramer 1991). Although it grows in Shetland, its foliage is often blackened by autumn gales (Scott & Palmer 1987). Elder occurred at 3% of stations on the Pembrokeshire Coast Path in a survey (Gulliver 1992) of exposed locations (excluding those in more sheltered areas such as bays and inlets). Elder was considered to have moderate to low tolerance to salt-laden winds, in comparison with Prunus spinosa (highly tolerant, present at 17.3% of stations) and Crataegus monogyna (moderately tolerant, present at 6.8% of stations). Young plants were slightly more frequent on south-facing than north-facing slopes in the Sheffield region (Grime et al. 1988). Sambucus nigra is characteristic of disturbed, base-rich and nitrogen-rich soils (Fl. Br. Isl.), and of phosphate-rich soils (Rackham 1986). High levels of available phosphate, available potassium and mineralizable nitrogen were observed in a series of soils from S. nigra sites (Table 1). The highest value of mineralizable nitrogen was recorded from a disused chalk quarry in Lincolnshire (sites 1 and 2) where rabbit grazing was evident. Other high levels were observed on a waterlogged soil on a stabilized flood plain (site 5), a domestic garden (site 8) and a scrubland area with a large elder population in a site with demolished buildings (site 11). Sites with the highest levels of available phosphate were the garden (site 8) and a mature, unmanaged hedgerow (site 7). Particularly notable were two sites on a sandy bank of the River Tyne (sites 3 and 4). These had low levels of the three major nutrients, although site 4 had higher levels than site 3, as expected because it was slightly further inland and more stable. Indeed, available phosphate was undetectable in site 3. Presumably, plants here derive their nutrition largely from periodic flooding of the river which brings dissolved nutrients and vegetable material. Generally, levels of available potassium were high, ranging from 24.0 to 610 µg g−1. Mean levels of the three nutrients with their associated standard errors were, for all sites; mineralizable N 118 ± 29.3 µg g−1, available P 43 ± 16.9 µg g−1 and K 310.9 ± 69.3 µg g−1. Mean levels for all sites except 3 and 4 were mineralizable N 136.9 ± 32.7 µg g−1, available P 51.8 ± 19.6 µg g−1 and available K 371.4 ± 69.4 µg g−1. Sodium contents of soils within 30 cm of elder bushes in two coastal sites were measured by flame photometry after aqueous extraction of the 2 mm fraction of air-dried soils for one hour. Values were 644 µg g−1 from Middle Head, Mumbles, Swansea (NG ref. SS632872), for a northerly facing seaward slope, susceptible to some sea spray, and 736 µg g−1 from Penclawdd, Gower (NG ref. SS547959), for a site c. 3 m above a tidal river bank, in an area which would occasionally be flooded with brackish water. These values suggest at least some degree of tolerance of saline conditions. See also the extemely high soil sodium values associated with industrial waste in Germany (section IV). Sambucus nigra exhibited lime chlorosis in six sites surveyed by Grime & Hutchinson (1967). In the Elbe valley above Hamburg, S. nigra grew in soils with mineralizable nitrogen values of between 12.3 and 16 mg of N per 100 cm3 of soil (total of nitrate and ammonium forms) after the soils had been incubated for 8 weeks at 30 °C (Meyer 1957). To compare these values with the present analyses, bulk densities were estimated from loss on ignition using the relationship of Jeffrey (1970). The mean mineralizable nitrogen of all 11 samples was 9.5 mg per 100 cm3 of soil. The range of values was 1.2–24.4 mg per 100 cm3, consistent with a wide range of habitats. In submontane broadleaved woodland and scrub in Central Europe, S. nigra grows on slightly acid to nearly neutral soils, which are damp to slightly wet (Ellenberg 1988). Ellenberg's indicator values for British plants assigned to S. nigra by Hill et al. (1999) were 6 for L (light level: tolerant of partial shade), 5 for F (moisture: mainly on fresh soils of average dampness), 7 for R (soil pH: indicator of weakly acid to weakly basic), 7 for N (nitrogen and general soil fertility level: often found in richly fertile places), and 0 for S (salt tolerance: absent from saline sites). The corresponding levels for Central European S. nigra (Ellenberg et al. 1991) were L 7, F 5, R value not given, N 9, and S 0. Field observations and the sodium content of soils in the vicinity of coastal elder bushes suggest that S. nigra is tolerant of mildly saline conditions. Experiments on leaf litter decomposition rates were undertaken by Bocock (1964) in which fallen leaves of several species were put in mesh bags, placed on soil and weighed after 27 days. On a mull soil, only 8% of the dry matter of S. nigra leaves and 25% of the original number of leaflets remained. On a moder soil, 24% of the dry matter was left, as was 57% of the leaflets. The total nitrogen content remaining after 27 days was 3% of the original on the mull soil and 22% on the moder. These decomposition rates were the most rapid of all the species tested, the only species with similar rates being Urtica dioica. The total nitrogen content of the freshly fallen leaves was 2.94% of dry matter and was among the highest of the species measured. Similar experiments were carried out by Cornelissen (1996) in which coarse- and fine-mesh bags of leaves from individual species were buried in litter mixture for 8 or 20 weeks. For S. nigra, the decomposition rate (expressed as percentage dry weight loss) in fine bags over 8 weeks was 48.6 ± 1.12; in coarse bags over 8 weeks, 92.2 ± 7.78; in fine bags over 20 weeks, 76 ± 2.59 and in coarse bags over 20 weeks, 100. The decomposition rates were high compared with the majority of species. Both Bocock's and Cornelissen's results demonstrate the extremely rapid decomposition of elder leaves under nearly natural conditions. As noted in section II (B), Sambucus nigra is associated with moderately to highly eutrophic soils. These are often soils subjected to disturbance either naturally as on floodplain terraces and woodland margins, or anthropogenically as in hedgerows, derelict gardens, farmyards and post-industrial wasteland. Sambucus nigra tends to be found in open or woodland edge situations. It sometimes occurs under deep shade in woodland but such bushes are often spindly and may often be survivors of former more open conditions. The communities in which S. nigra is found in Great Britain are listed below within the framework of the National Vegetation Classification (NVC). Sambucus nigra is an important component of Crataegus monogyna–Hedera helix scrub (NVC code W21) (Rodwell 1991). This community encompasses several of the most characteristic habitats of S. nigra, including hedges, derelict agricultural and post-industrial land, and is widespread throughout the British lowlands. Crataegus monogyna is the most frequent of the spinose shrubs in this community, followed in frequency by Rubus fruticosus agg. and many species of Rosa. Sambucus nigra is associated particularly with the Hedera helix–Urtica dioica and the Mercuralis perennis subcommunities on more mesotrophic soils and on man-made or fragmentary soils on derelict land where it is often accompanied by Buddleja davidii. In the Brachypodium sylvaticum and Viburnum lantana subcommunities, S. nigra is characteristic of locally enriched areas around rabbit warrens on the chalk. Elder is relatively abundant in species-poor hedges and its representation increases very little in species-rich hedges. This is in accord with its ability to colonize disturbed habitats quickly, and with its short life span (Pollard et al. 1974). It is unlikely that elder would be planted in hedges and its appearance is a result of its ability to plug gaps, usually (one presumes) by bird-deposited seed. Scattered shrubs of Sambucus nigra and Crataegus monogyna are present in the Pteridium aquilinum–Rubus fruticosus underscrub (W25), particularly in the Hyacinthoides non-scripta subcommunity. This community is dominated by the two constant species, Pteridium aquilinum and Rubus fruticosus, and commonly results from woodland clearance in agricultural or heath landscapes. The Hyacinthoides non-scripta subcommunity is widespread throughout lowland Britain, is most often found in woodland rides and clearings within wood-pasture and often dominates coastal cliff slopes in the south-west. Sambucus nigra and other shrubs are a sparse component of Rubus fruticosus–Holcus lanatus underscrub (W24), a widespread community of the British lowlands, typical of abandoned and neglected arable, pasture and gardens. Sambucus nigra can be prominent in patches, particularly in the more disturbed and enriched areas of Quercus robur–Pteridium aquilinum–Rubus fruticosus woodland (W10). It tends to be more frequent in the north-west, associated with Fraxinus excelsior, Ulmus glabra and Acer pseudoplatanus. It is commoner in the Acer pseudoplatanus–Oxalis acetosella subcommunity which is restricted to the upland margins of Wales, northern England and Scotland. In the Fraxinus excelsior–Acer campestre–Mercurialis perennis woodland (W8), S. nigra occurs throughout in patches and is locally abundant in more eutrophic conditions. It is more common where older stands have been disturbed or enriched. In the Geranium robertianum subcommunity, restricted to the north and west of England, S. nigra occurs in a higher frequency throughout, a result perhaps of the higher rate of nutrient turnover that occurs in these better aerated soils. This is in contrast to the stands in the south-east where S. nigra is very much an indicator of local enrichment and disturbance. Alnus glutinosa–Urtica dioica woodland (W6) is a community of eutrophic moist soils dominated by Alnus glutinosa, Salix spp. and Betula pubescens. Scattered bushes of elder dominate the shrub layer in the S. nigra subcommunity, which is particularly characteristic of sites of substantial deposition of mineral matter, such as on alluvial terraces or where enriched waters have flooded fen peats. Although moist enough for Alnus glutinosa to remain the dominant in all but the driest stands, the soils are in the most part dry towards the surface in the summer. This community is widespread but local throughout the lowlands. Sambucus nigra is one of the common elements of the shrub layer of Fagus sylvatica–Mercurialis perennis woodland (W12) along with Corylus avellana, Crataegus monogyna, Acer campestre and Ilex aquifolium. Fagus sylvatica is always the most abundant tree. This is a community of base-rich calcareous soils on the limestone scarps of south-east England. Where fires have occurred in mesophytic or calcicolous woodland, on railway embankments or derelict land, the Acer pseudoplatanus–Sambucus nigra subcommunity of the Epilobium (Chamerion) angustifolium community (OV27) often occurs (Rodwell 2000). This community is overwhelmingly dominated by Chamerion angustifolium, Rubus fruticosus and Pteridium aquilinum, and the woody species usually present are S. nigra, Acer pseudoplatanus, Fraxinus excelsior, Fagus sylvatica and Ulmus glabra. This community is widely distributed throughout the British lowlands. Alnus glutinosa–Fraxinus excelsior–Lysimachia nemorum woodland (W7) has a somewhat open canopy with Alnus glutinosa as the only constant tree. Sambucus nigra is most frequent in the Urtica dioica subcommunity where Fraxinus can be frequent. The understorey consists of S. nigra, Salix cinerea and saplings of Acer pseudoplatanus. The Urtica dioica subcommunity has eutrophic soils enriched by repeated deposition of material by flooding or flushing, but typically not so enriched as in W6 Alnus–Urtica woodland. This community has a wide but local distribution throughout the upland fringes of the north and west as well as the wetter parts of southern England. Sambucus nigra occurs sparsely and at low frequency in Fraxinus excelsior–Sorbus aucuparia–Mercurialis perennis woodland (W9), found in the wetter and cooler parts of Wales, west Scotland and north-west England. Sambucus nigra forms only a sparse and occasional component of the shrub layer of Fagus sylvatica–Rubus fruticosus woodland (W14), a type of beech wood confined to southern England, particularly well represented in the Chilterns and the New Forest. Elder is one of the few shrubs to be found in Taxus baccata woodland (W13), a community largely restricted to the chalk of the North and South Downs. Here the shrubs almost always reflect past association with rabbits. Hippophaë rhamnoides dune scrub (SD18) is a community of less mobile sand dunes around the coasts of Britain, being particularly well established on the east coast and has become naturalized in scattered localities between Devon and Cromarty (Rodwell 2000). Hippophaë rhamnoides is the dominant and the only constant species in this community. Sambucus nigra occurs in the more mature and denser H. rhamnoides stands, where it reflects the more nitrogenous soils which may be the result of nitrogen fixation by the root nodules of H. rhamnoides (Pearson & Rogers 1962). A provisional phytosociological catalogue of Irish vegetation (White & Doyle 1982) indicates communities in which S. nigra is a characteristic species. Polysticho-Asplenietum viridis is an association of damp walls, paths, canal banks and drains on nitrate- and phosphate-rich substrates. Diagnostic species include Phyllitis scolopendrium and Sagina procumbens. Sambucus nigra and Buddleja davidii often occur here. The association Salicetum albo-fragilis is a community of riversides, marshy woodland edges, ditches and hedges (White & Doyle 1982). Elder occurred in fewer than 20% of samples of this community (Kelly & Iremonger 1997). The class Rhamno-Prunetea is a woodland margin and hedgerow vegetation of bushes and shrubs interspersed with climbers. The class character species are Rubus spp., Sambucus nigra and Ribes uva–crispa. The association Primulo-Crataegetum, of this class, has the diagnostic species Crataegus monogyna, C. laevigata, Rubus spp., Prunus spinosa, Rosa canina, Rhamnus cathartica and Ligustrum vulgare. Many hedgerows can be ascribed to this association (White & Doyle 1982), and a map of hedges with Crataegus, Prunus spinosa, Fraxinus and Sambucus is given by O'Sullivan & Moore (1979). These are largely distributed throughout the southern part of Ireland from Meath southwards and as far west as Tipperary. Another group of hedgerow communities is included in the alliance Sambuco-Salicion capreae, with the diagnostic species Sambucus nigra, Salix caprea, Rubus idaeus and R. nessensis (White & Doyle 1982). The alliance Alno-padion encompasses species-rich alder woods. The presence of S. nigra and other nitrophilous species distinguishes this alliance from the Carpinion betuli alliance (White & Doyle 1982). Corylo-Fraxinetum is an association of the alliance Alno-padion. This is a community of base-rich free-draining soils over limestone. Of 41 samples of this type of woodland, S. nigra occurred in only 2 (Kelly & Kirby 1982). Sambucus nigra was present in fewer than 20% of stands of Betuletum pubescentis, a community of deep acid peat relatively well-drained in the upper layers (Kelly & Iremonger 1997). It corresponds with the Dryopteris dilatata–Rubus fruticosus subcommunity of the NVC W4 (Betula pubescens–Molinia caerulea woodland) (Rodwell 1991). The vegetation of Central Europe is described in great detail by Ellenberg (1988) from which the following account is summarized. Sambucus nigra is a variable component of brown-mull beech woods (suballiance Galio odorati-Fagion), the commonest type of beech wood in Central Europe whose soils range from rich to poor brown mulls. These woods typically have a high, dense canopy and do not normally have a well developed shrub layer. Mixed woodland rich in sycamore and ash is a widespread community type. Fertile soils are dominated by Acer pseudoplatanus, A. platanoides, Tilia platyphyllos, Ulmus glabra and Fraxinus excelsior. These are in deep, damp soils on or at the foot of slopes. Sambucus nigra is often here associated with Urtica dioica, Aegopodium podagraria, Silene dioica and Impatiens noli-tangere on soils rich in bases and nutrients, especially nitrate. Oak–hornbeam woods are a community of relatively dry climatic areas from Würzburg in the west as far as the central and eastern plains of Poland. Sambucus nigra is a variable component of the variants of Stitchwort–Oak–Hornbeam and Bedstraw–Oak–Hornbeam woods with damper soils. In river valleys of the lowland regions throughout Central Europe, woodlands of various mixtures of willow, poplar, elm and oak are the characteristic communities of flood plains. Elder is commonly found in many of these communities. On flood plains in the alpine coniferous region, grey alder (Alnus incana) woodlands predominate. Sambucus nigra is among the species here which can tolerate wet conditions. Another vegetation type with a Central European distribution is the Robinia pseudacacia–Sambucus nigra association of which three regional variants are described by Klauck (1988). The Western variant, found in the Rhine and Saar Valleys, Vosges and Lorraine has Acer pseudoplatanus, Carpinus betulus, Fraxinus excelsior and Quercus petraea as its major constant tree species. The Central European variant, whose major constant trees are Acer pseudoplatanus and Prunus serotina, is distributed principally in north-eastern Germany. The eastern variant, centred on the Czech Republic, Slovakia and Hungary, has the constant tree species Crataegus curvisepala. Many species of bryophytes and lichens are epiphytic on Sambucus nigra with Cryphaea heteromalla (Hedw.) Mohr, Zygodon viridissimus (Dicks.) R. Br. and Orthotrichum affine Brid. being particularly abundant (Watson 1981). In a transect survey of epiphytic bryophytes across southern Britain, Sambucus nigra held 17% of all epiphyte records, and was the species which accounted for the second greatest number of records, exceeded only by Fraxinus excelsior (Bates et al. 1997). It also has a distinctive lichen flora, with Xanthoria parietina (L.) Th. Fr. and Physcia aipolia (Ehrh. ex Humb.) Fürnr. being particularly characteristic. This epiphyte richness is probably due to the fact that elder bark has one of the highest water-holding capacities of any tree or shrub measured; between 371% and 465% of dry weight (Barkman 1958). Its bark is moderately acidic: pH between 5.7 and 7 (Barkman 1958). Elder will not establish where there is a turf. For example, grazing of chalk grassland at Ramsdean Down (Hampshire) may have kept the turf intact. Only after sheep grazing was discontinued around 1914 did the effect of rabbit scraping and frost begin the break-up of the turf. By 1940 a full invasion of elder had occurred (Hope-Simpson 1941). Sambucus nigra is, however, capable of establishing in a closed shrub canopy (Gilbert 1991), partially as a result of leafing earlier than most tree and shrub species. A study of the population dynamics of seven woody species in the Voorne dunes (near Rotterdam) showed that S. nigra was the only species to show a population curve without discontinuities. Most of the species showed a lack of recruitment in the 1960s and 1970s; in contrast S. nigra showed a continuous curve, which was very nearly linear when the numbers of individuals were plotted on a logarithmic scale (van der Maarel et al. 1985). This indicates a continuous recruitment of S. nigra seedlings, and that mortality was independent of age. Sambucus nigra was an occasional weed of winter cereals, probably brought to the field by birds. It grew better in plots treated by reduced cultivation and by direct drilling (Pollard & Cussans 1976, 1981). Sambucus nigra often invades hedges and is often regarded as undesirable (Marshall 1989). It was consistently controlled by 2,4,5-T and ammonium sulphamate (Fryer & Makepeace 1978). In trials in which 2-year-old seedlings of S. nigra were grown in pots and treated in June with half and full recommended rates of 15 herbicides and three plant growth regulators, Marshall (1989) noted that all plants treated with mecoprop, fluroxypyr and full rates of clopyralid and glyphosate were killed. Four months after application, vigour was reduced by the broad-leaved weed herbicides 2,4-D, fluroxypyr, ioxynil + bromoxynil and clopyralid, by glyphosate and by the highest rate of the plant growth regulator mefluidide. Sambucus nigra leaves contain cyanogenic glycosides (see section VI(F)) from which hydrogen cyanide is released by enzyme action. Although S. nigra is not generally considered poisonous, isolated cases of poisoning in animals and man have been reported after eating the bark, leaves, berries, roots and stems (Cooper & Johnson 1984). Two individuals of Jardine's Parrot died as a result of poisoning by elder leaves (Griess et al. 1998); these authors review the literature on the toxicity of elder and the cyanogenic glycosides, sambunigrin, zierin and holocalin. The numbers of insect species reported on elder is low compared with other woody species (see section IX(A)), and the presence of cyanogenic glycosides may in part explain this. The leaves, however, can be relatively palatable as shown by Edwards et al. (1986) who observed that 272 mg of undamaged S. nigra leaf material was eaten by the larvae of Spodoptera littoralis (Boisd.) over a 48-h period. This was a relatively high palatability in an experiment in which the lowest was shown by Populus tremula (42 mg) and the highest by Tilia × vulgaris (420 mg). Leaves damaged by punching 1 mm2 holes at 5 mm intervals were less palatable to the larvae than undamaged leaves collected from a different part of the canopy (Edwards et al. 1986). This effect was apparent when the leaves were removed for testing 14 days after damage, but not 2 days after damage. A similar pattern was observed when leaves adjacent to damaged leaves were tested. The bark contains many toxic lectins and ribosome-inactivating proteins (see section VI(F)). Toxic type 2 ribosome-inactivating proteins account for around 80% of the total bark protein (Van Damme et al. 1997b). Clearly, many defensive compounds are present in the various tissues of elder. These have a role to play in the complex interactions between plant and herbivore which are increasingly being uncovered (Schultz 2002). Rabbits are generally acknowledged to find elder unpalatable (Tansley, Br. Isl.; Fl. Br. Isl.; Gulliver 1992). However, a study of the relative palatability to deer of 16 trees and shrubs in a deciduous forest in southern Poland (Bobek et al. 1979) showed that S. nigra was one of the three most palatable species in the three types of forest studied. Sambucus nigra was resistant to severe pollution from a phosphate fertilizer factory in Germany. Soil pH was raised from 6.5–7.5 to 8.0–9.0, soil fluoride increased to 200 p.p.m. above normal levels and soil sodium content was more than 500 mg per 100 g soil (Heinrich & Schaller 1987). Sambucus nigra had low sensitivity to periodic exposures to ozone (0.2 p.p.m. for 5 h) throughout the growing season of 1976 (Davis et al. 1981).