Smyrnium olusatrum L.
2003; Wiley; Volume: 91; Issue: 2 Linguagem: Inglês
10.1046/j.1365-2745.2003.00761.x
ISSN1365-2745
Autores Tópico(s)Botanical Studies and Applications
ResumoTribe Smyrnieae. A stout, glabrous, celery-scented, semelparous, facultative biennial herb with thickened tap-root 50–60 cm and finer lateral roots near surface. One or more solid stems 50–150(−180) cm, becoming hollow at fruiting; branches in upper part often opposite. Furrows more apparent and deeper on upper stems. Leaves 2–3-pinnate or -ternate, dark green and glossy; lobes 25–80 mm, ovate to rhombic, serrate or lobed, with obtuse teeth, all stalked. Stem leaves with expanded sheathing petioles. Compound umbels axillary and terminal, subglobose with (3–)4–15(−18) rays (1–)4(−5) cm long with peduncle usually longer than rays. Terminal umbels with male and hermaphrodite flowers in ratio of about 4 : 1; lateral umbels mostly male. Hermaphrodite flowers can produce viable seed. Bracts and bracteoles entire, few or absent. Flowers c. 1.5 mm, yellow to yellow-green, actinomorphic, shortly pedicellate. Sepals small, stylopodium formed from styles with elongated bases. Black fruit a schizocarp, 7–8 mm, comprising two single-seeded mericarps, broadly ovoid, laterally compressed. Each mericarp with three distinct, sharp ridges and numerous vittae, which exude pungent myrrh-like oil. Air-dry mass of dispersules averages 20.5 mg (Grime et al. 1981) with seeds ranging between 2.5 and 4.0 mg. An introduced species fully naturalized in hedgerows, roadsides, railway embankments, waste places and cliffs, mainly near the sea. Inland sites are frequently associated with old dwellings or ruins, especially monasteries or castles, where it is probably a relic of kitchen gardens. No significant intraspecific variation is known in Britain (Tutin 1980). In England Smyrnium olusatrum (Alexanders) is locally common in hedgerows, hedged banks, sea cliffs, quarries, railway embankments and, occasionally, in woodland (e.g. Overhall Grove, Cambridgeshire). It is abundant in the southern coastal counties from Norfolk to mid-Wales (Fig. 1). Salisbury (1952) included it as a fixed dune species. It is also common on the east coast of Ireland but is less frequent on the west coast and scarce in Scotland. It is not present north of a line from Dumbarton to Banff except for a few isolated coastal locations that are recent records. Coastal colonies seldom extend beyond 5 km inland and are commonest within 2 km of the sea. Inland sites are usually related to sites of previous habitation. Mullin (1967) recorded S. olusatrum as an exotic weed of South Shields parks. The distribution of Smyrnium olusatrum in the British Isles. (○) pre-1950, (•) 1950 onwards. Each dot represents at least one occurrence in a 10-km square of the National Grid. Mapped by Henry Arnold, Biological Records Centre, Centre for Ecology and Hydrology, mainly from records made by members of the Botanical Society of the British Isles. In Europe and beyond, the species ranges from countries bordering the Mediterranean basin to its northern limit in Scotland (Fig. 2). Hultén (1958) indicates that it does not grow in Feno-Scandia, its northernmost continental limit being Denmark (Fl. Eur. 2). Throughout its range S. olusatrum is favoured by shelter from extreme frost or sea cliffs. Blamey & Grey-Wilson (1993) record it from damp places, woodland margins, damp dunes and coastal cliffs. It is well-established on islands in the Mediterranean where its presence may often result from human agencies, as fresh seeds do not float (see Section VIII(c)). Davis (1972) also mentioned sea-cliffs to 300 m and phrygana (coastal scrub) in Turkey where its northern limit appears to be the Caucasus Mountains. Ulubelen & Öksüz (1970) described S. olusatrum as abundant around Istanbul, where it grows 1–2 m in height, and common elsewhere in coastal areas of western and European Turkey. Turland et al. (1993) specifically mention olive groves and old walls in Crete and Karpathos as important locations for this species. Pignatti's (1982) map of Italy shows S. olusatrum present in all plant recording units. In the Ronda Valley, southern Spain, M. Southam (pers. comm.) describes it as abundant on the upper face of the gorge. In Ibiza it is favoured by sheltered areas around old buildings and walls. Palhina (1939) described S. olusatrum as infrequent on the matos of Portugal. Towards the northern limit of its continental range, Kloos (1951) and Ooststroom (1952) recorded it in the Netherlands, the latter record (from 1944) re-establishing the earliest Dutch record of Commelin in 1683 for the island of Texel. According to Press & Short (1994) S. olusatrum has been recorded once from Madeira, in Funchal, probably as a casual. Trelease (1897) mentioned it as having been recorded in the Azores but not recently collected. The world distribution of Smyrnium olusatrum. Source Floras of various countries: Bicknell (1896), Bonner (1982), Cash (1933), Davis (1972), Fl. Eur. 2, Fournier (1977), Garcke (1972), Gibson (1862), Gjerum et al. (1982), Haeupler & Schönfelder (1988), Hanbury & Marshall (1899), Hegi (1926), Jermyn (1974), Kloos (1951), Koch (1902), L'Ecluse (1557), Oberdorfer (1978, 1983), Ooststroom (1952), Pignatti (1982), Polunin & Huxley (1974), Skene (1939), Sousa da Camara (1932), Strid (1986), Turland et al. (1993) and Wolley-Dod (1937). Mabberley (1997) refers to S. olusatrum as naturalized in Bermuda – the only New World record. This may be related to a chance transfer of seed in the mid-19th century since in 1853–54 the 56th Essex Foot Regiment were reviewed by Lord Connaught on the cliffs of Great Holland, Essex (currently and historically a S. olusatrum site) immediately prior to being posted to Bermuda (Emmison 1969). The most northerly site for S. olusatrum is at Portsoy, Banff, where a colony grows on the south-facing slope of the banks of the Burn of Boyne at 35 m a.s.l. on limestone in partial shade under Acer pseudoplatanus, Sambucus nigra and Crataegus monogyna. Smyrnium olusatrum is a sea level or lowland plant (Alt. range Br. Pl.). Some higher altitude sites are known in the Isle of Man, where there are some single plant records on the foothills and slopes in the central valley between Douglas and Peel at 100–150 m. The highest record for the Isle of Man is at 165 m on cliffs to the south-east of Peel. The only other record from a higher altitude site in Britain was a plant at almost 200 m in the Cotswolds (M. Southam, pers. comm.) but this did not survive to flowering. All distribution maps of Smyrnium olusatrum clearly illustrate its maritime or sub-maritime nature (1, 2). The distribution map for Devon (Ivimey-Cook 1984) is particularly interesting as the county has distinctly separate north and south coastlines, with S. olusatrum records decreasing rapidly inland from both. In the Balearic Islands (Bonner 1982) S. olusatrum occurs in cool and shady places as in many Mediterranean sites. In Britain this is less true of all coastal sites, as many are south-facing (e.g. in Wales at Tenby Cliffs, St David's coastal footpath), but some shelter is significant. In the west of Britain, plants often grow within the shelter of stone-walls which replace hedging, while in the south and east a roadside verge/hedgerow location is commonplace. The only known site from Cleveland at the mouth of the River Tees is generally exposed, but the location is in a hollow on the sheltered side of a breakwater (P. Lawrence, pers. comm.). Inland colonies may be along the shelter of canal-sides or railways where ground has been disturbed in the past, but the most common locations are adjacent to old buildings. A classic site in Wales is the castle mound at Tenby. In Ireland there are extensive colonies at Portora Castle, Enniskillen; Aghalane Castle, Upper Lough Erne; Old Castle, Ventry; Castle Lough and at the abbey ruins of Ballinskelligs and Abbydorney. In Scotland the only location for Ayrshire is both coastal and an old habitation: seaside rocks at Culzean Castle, and on Arran there is a population of around 100 plants on the south-facing cliffs near Kildonan Castle. Other Scottish sites are Craigmillan Castle, Midlothian and Dulton Castle, East Lothian. In Cambridgeshire there is a colony at Overhall Grove, Knapwell on the earthworks of a manor house abandoned in the Middle Ages. This population is on a boulder clay moat embankment on the south face of a sloping site under a canopy of Ulmus minor. The site in Essex at Witton Wood Spinney and that in Suffolk at Greyfriar Wood, Dunwich, are Ulmus procera woodlands. In Guernsey too, a favoured site is partial shelter under Ulmus stricta, and many of the East Anglian hedgerow sites are under the suckers of Ulmus minor or U. plotii. The partial shelter offered by these late-leafing, small-leaved species seems ideal for S. olusatrum. The distribution data in Fig. 3 suggest that S. olusatrum sites in Britain are at the limit of the plant's temperature tolerance, especially in summer but also in winter. Dr M.C.F. Proctor (pers. comm.) noted that, like Lithospermum purpureocaeruleum, S. olusatrum seems typical of cool sites in the Mediterranean but warm sites in Britain. It would appear to be best assigned to the Mediterranean–Atlantic floristic element of Preston & Hill (1997), thriving well where there is minimal frost and adequate moisture. The occurrence of Smyrnium olusatrum relative to the mean temperature of the warmest and coldest months. Open circles (○) represent the presence in the British Isles and filled circles (•) presence elsewhere in the world. The broken line gives the inferred thermal limits for this Umbellifer. Records of occurrence were taken from Floras and herbaria (see caption of Figure 2); temperature data were derived from climatological Atlases for sites adjacent to those where the plant occurs. In Britain S. olusatrum grows predominantly in alkaline to neutral substrates, although in some of its near-coastline locations it grows in silica-rich sand. Almost all of its inland sites are on chalks, limestones or neutral to lime-rich clays, but nearly all these sites are also at or near old human habitation. French et al. (1999) remark that S. olusatrum is now being more frequently recorded inland on roadsides and hedgebanks in Cornwall, but remains rare on granite uplands. It is, however, frequent on blown sand over granite on the Isles of Scilly where Lousley (1971) regarded it as 'an ancient potherb, now completely naturalized'. Because of the free drainage of all coastal sites of S. olusatrum, no location was recorded with conductivity greater than 500 µS cm−1 or Na of 2.85 m.e. exchangeable cations 100 g−1 oven-dried soil. Unusually S. olusatrum on the Isle of Man occurs in greatest numbers on the free-draining acid soils of the north-west with a pH of 5.0–5.5. These sandy loams or sandy clay loams receive higher rainfall than many S. olusatrum sites and this may ameliorate the habitat. Somewhat similar behaviour is found in Cladium mariscus which is normally associated with the alkaline fens of East Anglia, but which also occurs in high rainfall acid bogs of Ireland. Throughout its entire range Smyrnium olusatrum is recorded as occurring with a wide variety of associated species in differing habitats. A precondition of growth seems to be an open habitat with enough bare ground for limited initial competition. Once established, however, the species may become dominant; its persistence and vigour allow its survival despite substantial changes in the vegetation around it. Except for a few inland wooded locations, the majority of sites are some form of semi-natural permanent grassland. In three British locations, Portland Bill (Dorset), Steep Holm Island (Somerset) and Puffin Island (Anglesey) S. olusatrum has become the dominant species over several hectares (Legg 1995). In continental Europe S. olusatrum occurs on cliff-top grassland, cliff/gorge faces and along roadside verges, usually close to human habitation, but frequently in greater shade than in Britain. In Britain, the species is found within a number of associations from upper beach to fixed dune, through neutral unimproved grassland to calcareous grassland and woodland. Table 1 lists species recorded with S. olusatrum in habitats visited by the author. Several are clearly related to those described by Rodwell (1991, 1992, 2000). These are briefly reviewed here. Fraxinus excelsior–Acer campestre–Mercurialis perennis woodland, W8, with invasive suckering elms. This community occurs on the heavy claylands of East Anglia (Peterken 1980; Rackham 1987). Suckering elm extends readily over abandoned settlements, as at Overhall Grove, Cambridgeshire, where there is often much dead wood and timber enriching the soil and quite high light flux through the canopy, especially with the cycles of Dutch Elm disease (Ceratocystis ulmi). In such locations where S. olusatrum has been recorded, it usually grows vigorously. Prunus spinosa–Rubus fruticosus scrub, W22. This community is characteristic of mesotrophic mull soils of moderate base-status, either where grazing has been relaxed or in exposed sites. It is found on several of the islands where S. olusatrum is abundant often as a marginal belt. Rubus fruticosus–Holcus lanatus underscrub, Arrhenatherum elatius–Heracleum sphondylium subcommunity, W24b. This community has affinities with Arrhenatherion grasslands. It occurs commonly on the landward side of borrow dykes and to the rear of road verges in East Anglia. The community is quite rich in ruderals and also found widely in neglected sites. Dactylis glomerata is common and S. olusatrum occurs as dense stands within the community. Arrhenatherum elatius grassland, MG1. This is the community in which S. olusatrum most commonly occurs. Other large umbellifers (Anthriscus sylvestris, Conium maculatum, Heracleum sphondylium and in north-east Essex Peucedanum officinale) are common throughout and sometimes abundant with sequential flowering. Apart from Centaurea nigra, Cirsium arvense and Urtica dioica, other tall herbs are generally infrequent. Beneath these taller species, there is usually a layer of coarse tussock grass and fine-leaved grasses, small dicotyledonous plants and sprawling legumes. Urtica dioica–Galium aparine community, OV24. This community of open habitats comprises generally species-poor tall-herb vegetation dominated by often densely abundant Urtica dioica, frequently growing over 1 m high by mid-summer. Galium aparine is the only other constant throughout and it usually forms sprawls among the nettles. Typically there are scattered plants of Cirsium arvense and Anisantha sterilis and coastal stands frequently have S. olusatrum, sometimes in local abundance. The commonest location of such stands is on the upper strandline detritus of beaches and salt-marshes, but it is also frequent on ill-managed recreational areas near the sea. Parsons (in Legg 1985) reports that no evidence has been found of S. olusatrum in the stomach contents of muntjac deer (Muntiacus reevsi) on Steep Holm, although the Somerset Archaeological and Natural History Society (1981) describe stems of Alexanders gnawed by muntjac between 10 cm and 50 cm. Legg (1993) reports that rabbits also gnaw the lower stems and often topple the plants and in the drought year of 1984 rabbits browsed on the plant when their population reached c. 250 animals, and other food sources could not support them. The rat (Rattus norvegicus) on Puffin Island, Anglesey, has been recorded burrowing 10–15 cm into the soil to eat the root-stock. McClintock (1975) refers to the records of N. Jee on Guernsey 'where it has been observed that horses consider it (Smyrnium olusatrum) a delicacy but cows leave it alone unless exceptionally hungry'. Tiddy (1946) noted that 'horses and donkeys prefer the wild and prolific weed Alexanders to grass or better food' in the Isles of Scilly. Trampling is not a major threat. A few plants have been seen to be dwarfed by trampling adjacent to footpaths in the north-east Essex sites. No records are known of the effect of trampling by animals. The castle mound at Tenby has a substantial colony of S. olusatrum in the unmown rough grassland to the north, but the plant is absent from the closely mown greensward to the south, suggesting that constant mowing may well have eradicated it. Road verges cut before May allow plants to reach flowering in late summer and set viable seed but later cutting, although leading to rapid regrowth, does not usually result in viable seed production. Performance in the early stages of growth is greater in areas of bare soil compared with vegetated ground. Once established, the surrounding vegetation probably has relatively little effect on the plants as growth is vigorous and shade from the leaves may weaken or kill the plants over which leaves of S. olusatrum spread. The major effect of other plants at most S. olusatrum sites is to provide the necessary part-shade and equability of microclimate favoured by the species. On Puffin Island, Anglesey, this is provided by Sambucus nigra (Griffin et al. 1968) and at the Naze, Walton, Essex, by a spinney of Ligustrum ovalifolium, Salix spp. and Rubus fruticosus agg. At Frinton-on-Sea, Essex, the small colonies on the greensward are centred on Tamarix gallica bushes. In optimal conditions, S. olusatrum grows in almost pure stands with few other species in competition. Elsewhere it is more scattered within grassland or below scrub/light woodland communities. Contagious distribution (sensuKershaw 1973) may be the result of three factors: (i) microhabitat, (ii) good years for seed dispersal, and (iii) clonal development over long periods. The first two factors are particularly important for this species. On Puffin Island, Beaumaris, Anglesey (R.W. Arnold pers. comm.), pure stands of S. olusatrum extend over large areas of the island mainly in the shelter of Sambucus nigra. On steeper near-shore slopes it grows in rough grassland. The island was inhabited by monks from the 7th century to 1556 and has since supported extensive Larus argentatus (herring gull) colonies (15 500 pairs in 1970, c. 7000 pairs in 1990) resulting in zooplethismic nutrient enhancement. On Steep Holm, where it was introduced by the medieval Augustinian Canons, Urtica dioica plants grow among the S. olusatrum and take over from it by mid-summer. Light starvation caused by S. olusatrum is severe between May and July and blocks any potential competition (Kenneth Allsop Trust & Fowles 1978). Steep Holm Island, Somerset, is Carboniferous limestone, with Smyrnium olusatrum being the dominant plant on the island, covering around 8 ha (Skene 1939). Kenneth Allsop Trust & Fowles (1978) describe it as forming a summer mini-forest all over the flatter expanses of the island, alternating in places with Conium maculatum, another important plant in the medieval pharmacopoeia. Because S. olusatrum extends from the splash zone up the cliffs and forms extensive meadows on the relic farmland (it covered 51% of the island in May 1975), it is mentioned annually in the Steep Holm Natural History Reports (e.g. Parsons 1994, 1996, 1998, etc.). These form the single most abundant reference for any S. olusatrum colony. The success of the species at this location is thought to be due to a combination of factors including the thin (15 cm) layer of alkaline soil over limestone, the cool but equable maritime environment, and the cessation of farming around 1930 which allowed a rapid expansion and the build-up of Larus argentatus and Larus fuscus colonies to a peak of c. 8000 pairs in 1974, whose faeces add very high levels of phosphate and nitrate to the soil. In 1985 and 1986 there are references to wet springs bringing about a failure of the S. olusatrum cycle and the invasion of Senecio jacobaea. Plants on roadsides in East Anglia where hedgerows have been removed are noticeably less robust than those in sheltered colonies. Plants by roadside stone walls in the west of Britain rarely exceed 1 m in height. The importance of shelter is noted in Section IV(C). This extends beyond biotic shelter, however. Plant growth at North Shields is limited to the lea side of the Collingwood Monument. At Broadstairs and Frinton, the best growth occurs behind beach huts, and at Bawdsey, Suffolk, the most vigorous plants are within the protection of the sea defences. Frost is infrequently experienced at coastal locations where S. olusatrum grows in Britain. However, penetrating frost occurred to colder than −5 °C during the winter of 1987 on the coast of north-east Essex and extensive colonies were damaged on Mersea Island and at Lower Kirby, with seedlings killed and yearling plants knocked back to ground level. However, the root-stocks remained viable and regrew flowering stems later in the year. Frost of a similar intensity in January 2001 wiped out all seedlings in the Langenhoe (Essex) colony, but second year specimens were fully recovered and in flower by late May. Parsons (1998) reported that, in 1996, Alexanders leaves were withered and brown on 5 May after a frost at dawn on Steep Holm. An Iversen plot (Fig. 3) shows that in Britain S. olusatrum is near the thermal limit with respect to the coldness of the winter, but especially the lowness of the summer temperatures. Only the colonies in Denmark, on Texel and along the coast of the Cherbourg Peninsula had similar temperature regimes. Parsons (1996) described all plants of this species on Steep Holm as 'having succumbed to hot, dry weather in July 1995', but this is more likely to be an example of aestivation. The colony at Wrabness on the southern shore of the River Stour, Essex, was severely damaged in 1989 with many plants withered and dead as a result of salt-water inundation brought about by an unseasonable westerly gale. The virtual absence of S. olusatrum from Lincolnshire and the Dengie area of Essex may be attributed to the frequency of coastal inundation at otherwise suitable sites in these areas. No evidence has been recorded of this species suffering from drought in Britain. A large colony of S. olusatrum at the Naze, Walton, Essex, grows from the cliff top to the back of the beach. The plants on sand have been observed buried to a depth of 36 cm. Natural blanching of the celery-like stems occurs but no reduction in vigour was noted. The allocation of biomass in selected umbellifers has been investigated by Lovett-Doust (1980a). He found that at maturity S. olusatrum allocated 25–39% of its biomass and 60% of total phosphorus to reproductive tissue. The first season's growth is dominated by the development of a massive root storage system. Figure 4 (after Lovett-Doust 1980a) shows the proportionate allocation of biomass during the life cycle in (a) autumn and (b) spring germinating plants. Most adult plants attain c.100 g dry weight in the field. The greater proportion of this is root tissue for the first 15 months of growth until flowering. At this stage the root biomass decreases both in relative and absolute terms over a period of 7 months as stems, peduncles and reproductive tissue are formed. Proportionate allocation of biomass during the life cycle of Smyrnium olusatrum in (a) autumn germinating and (b) spring germinating plants. (After Lovett-Doust 1980a) Lovett-Doust & Harper (1980) found that before fertilization S. olusatrum plants distribute around a fivefold greater proportion of phosphorus to male rather than female organs. However, the cost of placental support of developing embryos reverses the ratio such that at seed maturity twice as much phosphorus is allocated to seed as to stamens. According to Guyot (1972), S. olusatrum has a primitive stomatal development with a mesoperigenous anomocytic stoma as the norm, but in which the development is partly accomplished according to the anisocytic mesoperigenous type. Mean stomatal densities were determined from material collected at Langenhoe, Essex (TM0018). Stomata are present on both adaxial and abaxial leaf surfaces. Stomatal densities of mature leaves are some 20% lower from more shady sites (under scrub) but in normal hedgerow conditions the following values were recorded (n = 20): upper (adaxial) surface 140–175 mm−2, lower (abaxial) surface 60–85 mm−2. The root (Fig. 5) is initially a deep, narrow tap-root (50–60 cm). The upper part thickens early as root reserves accumulate and may reach a diameter the size of a human wrist (Legg 1993). During the first summer, multiple (2–3) curved branches develop. The largest root branches grow subvertically with finer branches extending laterally in the upper soil-layers. Lovett-Doust (1980a) recorded a ratio of up to 0.54 below-ground : above-ground tissue at mericarp maturity in specimens from Anglesey. Root of Smyrnium olusatrum after 500 days' growth. Examination of root-material in August 2000 taken from Overhall Grove, Cambridgeshire, showed the presence of vesicular-arbuscular mycorrhizas (Irene Johnson and J.R. Leake pers. comm.). Smyrnium olusatrum is a facultative biennial, usually flowering in the second year, with a tuberous tap root which develops in the first year. It is monocarpic, flowering once before dying. Under extreme conditions reproduction may be delayed for more than one calendar year. Lovett-Doust (1980c) found a floral ratio at full maturity of four male flowers to one hermaphrodite flower constant in S. olusatrum, Pastinaca sativa and Anthriscus sylvestris with between 55–70% of hermaphrodite flowers producing viable seed. Lovett-Doust & Lovett-Doust (1983) showed this to be true despite very different total numbers of flowers per plant, following Lloyd's (1979) canalized gender strategy, in which as the season progresses the proportion of male flowers increases to minimize direct competition within a plant between maternal and paternal reproductive activity. Autumn-germinated seedlings retain cotyledons for approximately 30 days, whereas late winter seedlings lose their cotyledons after about 25 days. Above-ground parts of vegetative plants often die back in mid-summer and remain absent until mid-autumn. Plants usually begin to develop inflorescence material late in the following January. The whole period of flowering and fruit maturation lasts about 220 days by which time the root begins to rot and cauline leaves die. Thus the minimum life-cycle is 580–670 days, depending upon germination date. Occasional plants persist into a third year before flowering. Although uncommon, M. Gillham (pers. comm. 1990) and the author have observed seed germinating in beach sand in North Wales and Walton, Essex. 2n = 22 (Chr. Eur. P1.) both in Britain (Rutland 1941; Moore 1971) and continental Europe (Delay 1947). In laboratory growth studies (Lovett-Doust 1980b) it was shown that plants grown in a heated glasshouse with high/low nutrient regimes, deradication and defoliation, had vastly different patterns of allocation of dry matter and phosphorus across the plant. Figure 6a,b shows the range varies from 21–74% of total phosphorus and 12–35% dry matter within reproductive tissue. (a) The patterns of allocation of dry matter in flowering plants of Smyrnium olusatrum at the time of ripe fruit (calculated excluding any excised tissue). (After Lovett-Doust 1980b). (b) The patterns of allocation of total phosphorus in flowering plants at the time of ripe fruit (calculated excluding any excised tissue). (After Lovett-Doust 1980b) The amounts of phosphorus present in different plant organs reflect in part the different allocations of biomass to the different categories of organ. Particular structures are seriously depleted of phosphorus during the process of reallocation at fruit production. This suggests that the death of monocarpic plants after seed set may be a direct consequence of the depletion of resource levels in vegetative tissue below that necessary to sustain future meristematic growth or loss of meristems themselves after floral initiation. In field locations in Britain, water availability does not seem to limit growth. However, salinity is significant with no plants recorded growing below High Water Mark High Spring Tides, even though the vast majority of plants occur in sub-maritime locations. Timing of flowering and seed-production, studied over many years of differing temperature conditions, suggests that S. olusatrum is a long-day species. However, chilling may also be involved in the regulation of floral development. All umbellifers produce essential oils and biochemically related resins secreted in canals in roots, stems, leaves, inflorescences and in the vittae of fruits (Hegnauer 1972). Crowden et al. (1969) describe several members of the genus including S. olusatrum as containing kaempferol and quercetin. The majority of Apiaceae give positive results for flavonoids with Smyrnieae predominantly containing flavonols rather than flavonones. Smyrnieae are particularly noted for their furocoumarins and acetylenic compounds. Ulubelen & Öksüz (1970) used thin layer chromatography on stem and leaf tissue from S. olusatrum and showed the presence of quercetin-3,7-diglucoside and kampferol-3,7-diglucoside as well as several phenolic acids. However, Harborne & Williams (1972) question the presence of 3,7-diglucosides although samples from 15 locations over a wide geographical range showed quercetin and isorhamnetin 3-glucosides uniformly present as seed flavonols. Ulubelen et al. (1971) identified two sesquiterpenic lactones in roots of S. olusatrum which were named istanbulin-A and istanbulin-B. The former is of an eremophilenolide type. The latter is present in minute quantities only. Ulubelen & Öksüz (1984) found that fresh root tissue contained only 25% of lactones present in dried roots, whereas chloroform extracts yielded 50 times the levels of lactones. This suggests that reports of large amounts of sesquiterpene lactones from plants that produce furanosesquiterpenes may be a result of the extraction methods
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