Portal de Periódicos da CAPES

Ornithogalum pyrenaicum L.

2000; Wiley; Volume: 88; Issue: 2 Linguagem: Inglês

10.1046/j.1365-2745.2000.00446.x

1365-2745

Darryl J. Hill, Benjamin Price,

Plant Physiology and Cultivation Studies

Section Beryllis (Salisb.) Baker. A vernal perennial geophyte with long, narrow, slightly glaucous, glabrous leaves. Bulb white, ovoid; about 50 mm in diameter when mature, with brown papery covering scales and a pronounced base plate (stem). It produces small (2–4 mm) fusiform bulbils at the base. The 5–8 leaves (all basal) are dull, linear, 10–15 mm broad, parallel-sided, 400–750 mm long, straight and slightly U-shaped in section when young. They can be distinguished from leaves of Hyacinthoides nonscripta by their glaucousness. The leaves wither early at anthesis (June–July). The scape, at 0.5–1 m, is one of the longest in the Liliaceae in Britain. There are 20–40 or more flowers on the raceme which markedly lengthens as anthesis proceeds up the stem. The six linear perianth segments, 11–13 × 2.5–3 mm (Fl. Eur. 5), 6–13 mm (Stace 1997), have a greenish stripe (darker on the outside) and become yellowish with age. At the same time the dorsally fixed pale yellow anthers turn to become at right angles with the filaments and darken. The nectary is at the base of the ovary and nectar is secreted by three septal glands (Knuth, Poll. 3, p. 450). Ovary 2.4–3 mm, ovoid-lanceolate or shortly cylindrical, truncate at base, with a single style 2.5–3.3 mm long. After pollination, the lower flowers mature to form 1–40 capsules, with the upper flowers and scape withering and abscising. Capsule ovoid, 8 mm long, 3-grooved, containing 5–10 black angular seeds (5.5–6.5 mg air-dry weight) some of which may, after ripening and dehiscence in late summer, remain in the capsule until winter. The only other species of Ornithogalum naturalized in Britain (Stace 1997) belong to different sections of the genus. Ornithogalum (Sect. Ornithogalum) angustifolium Boreau (= O. umbellatum auct. non L.) is native and grows in grassy places over most of Britain and has a corymbose inflorescence. The closely related O. umbellatum L. is an introduced species whose bulb forms numerous bulbils (Stace 1997). O. (Sect. Myogalum) nutans L. (introduced) has larger flowers (20–30 mm) in a 2–12 flowered unilateral inflorescence. There are no reported British subspecific taxa of O. pyrenaicum. However, there are considerable taxonomic problems within the genus in southern and south-eastern Europe owing to very similar but phenotypically plastic species which form poor quality herbarium specimens. The most complete taxonomic review is by Wittman (1985) who deals with 16 species, two of them aggregates. The species are mainly separated on floral and fruit characters. Moret et al. (1986) have used numerical taxonomic techniques in confirming the identity of O. pyrenaicum in N. Africa. In a wider context, O. pyrenaicum is placed by some authors in the Hyacinthaceae, being related to Hyacinthoides nonscripta (bluebell), a much more widespread and abundant vernal plant in Britain whose ecology is better known (Woodhead 1904; Blackman & Rutter 1954; Graham & Packham 1983). In several features the two species are similar and may make a helpful comparison. Vernacular names include Spiked Star of Bethlehem (Dony et al. 1986) and Bath Asparagus. Ornithogalum pyrenaicum is a scarce, but locally abundant, native plant in southern England, growing in woods, hedgerows and grassy verges, mostly on clayey soils overlaying limestones or gravels. Ornithogalum pyrenaicum is close to its northerly limit in Britain where it is mainly located in the Bath area (Fig. 1) in Wiltshire (Green 1993), Somerset (Green et al. 1997) and Gloucestershire (Riddelsdell et al. 1948). It also appears to be native in Bedfordshire near Eaton Socon (Dony 1953) and in Berkshire in woodland (Ashridge Wood) on the chalk (Druce 1897). Elsewhere (e.g. Shropshire, Surrey and Suffolk) it is believed to have been introduced (Atl. Br. Fl.). There are two other stations where it is possibly native in southern Britain making a total of 23 hectads (and 95 tetrads) where it is recorded native (Stewart et al. 1994) and its national status is scarce. Within areas where it occurs, it may comprise variously sized subpopulations that are disjunct. O. pyrenaicum in Britain is a lowland plant, occurring below 180 m above sea level. The distribution of Ornithogalum pyrenaicum in the British Isles. Each dot represents at least one record in a 10-km square of the National Grid. Mapped by Mrs J.M. Croft, Biological Records Centre, Institute of Terrestrial Ecology. Native: (○) pre-1950, (●) 1950 onwards; introduced: (+) pre-1950, (×) 1950 onwards. Classified as a Submediterranean–Subatlantic species by Preston & Hill (1997), O. pyrenaicum extends in its wider distribution to N. Africa in the south and possibly Greece and Turkey in the east (taxonomic uncertainty), but the species is apparently most common in N. Yugoslavia (Fig. 2). In Morocco it occurs in humid biotopes (spring areas at the foot of cliffs, riparian forests and high-elevation humid forests) in the Atlas Mountains with two other very similar species of Ornithogalum, and its identity was confirmed from material collected at 900 m in the Mid Atlas using statistical techniques (Moret et al. 1986). In much of western and central Europe, it appears to be a scarce species restricted to localized populations; for example, in Saarland, Germany, it is rare as a small population in need of conservation (Wetter 1981). As in Britain, the fact that the plant has occurred over a considerable time in local isolated populations in undisturbed sites (hedges, woodland and scrub) suggests that the plant may be a relic. The distribution of Ornithogalum pyrenaicum in Europe and western Asia. The map is based partly on those of Wetter (1981) and Wittman (1985). (●) records from herbarium specimens and the literature; (□) herbarium records of the Macedonia-Asia Minor form of the plant. The largest populations in Britain are in the Bath and Keynsham areas in valleys on both north- and south-facing slopes. O. pyrenaicum grows abundantly in woodland and hedgerows, often along green lanes and in scrub, but is not so frequent in open fields unless associated with bramble or bracken patches or on sites previously occupied by woodland. In Britain, it occurs close to the 5 °C January and 16 °C July isotherms (based on 1901–1930 daily means) and within 60–100 cm annual rainfall isohyets. In continental Europe, it occurs in regions within a mean surface temperature range for January of −15 to 10 °C and for July of 15 to 25 °C, and within a mean rainfall range for both winter (1 November to 30 April) and summer of 15–100 + cm and a total mean annual rainfall range of 50–200 + cm. The above climatic data suggest that the limit to the distribution of O. pyrenaicum in Britain may depend, in part, on summer temperatures. The soils in which O. pyrenaicum grows are clayey but moderately well drained or on clay over well-drained lower strata. For example, it is abundant on Keuper Marl and Blue and White Lias (Keynsham); Fuller's Earth and Midford Sand (south of Bath); and Gault overlying gravel (at Eaton Socon, Bedfordshire) and on clay soils over the Great and Inferior Oolite limestone. The soils are neutral (pH 6.7–6.9) with near to 100% base saturation (four sites in Bath area). Comparison of the distribution of the plant with the Soil Survey maps shows no discernible correlation between its distribution and that of any one soil association, although the plant mainly occurs in the Bath area on the Evesham 1 and Elmton 1 Associations which include clayey soils over calcareous substrata (Findlay et al. 1984). In Saarland, Germany, it occurs in oak and hornbeam woods on nutrient-poor loam soils of pH 5–6 (Wetter 1981). Most plants are on well-drained soils and in woodland often in association with Mercurialis perennis, a species particularly intolerant of poorly drained soils. The woods in England in which O. pyrenaicum occurs abundantly have a high canopy and low herb layer; it is present mainly in W8 Fraxinus excelsior–Acer campestre–Mercurialis perennis woodland of the National Vegetation Classification (NVC), occurring in the W8b Anenome nemorosa, W8e Geranium robertianum and W8f Allium ursinum subcommunities (Rodwell 1991). It has also been reported from the NVC W6 Alnus glutinosa–Urtica dioica community (W6d Sambucus nigra subcommunity). In woods with tall herbs and thick shrubs, it is sparse or absent. In hedgerows, however, O. pyrenaicum grows among herbs 0.5 m tall and on grassy road verges (Eaton Socon, Bedfordshire) in ungrazed grass about the same height in NVC MG1 Arrhenatherum elatius grassland, MG1a Festuca rubra subcommunity (Rodwell 1992). Species commonly associated with O. pyrenaicum are given in Table 1 & 2. The woodland and hedgerow sites had similar species lists of common plants with few other uncommon plants. The hedges were rich in shrub species and could be woodland relics but compared with woods had more shrub species and a predominance of maple. This contrasts with O. pyrenaicum in Saarland (Wetter 1981) where it occurs in oak/hornbeam/aspen woods but with a similar hazel/hawthorn/bramble understorey and a species-rich herb layer characteristic of a more acid soil than where O. pyrenaicum occurs in Britain. Oberdorfer (Pfl. Exk. 1990) also records it in oak-hornbeam woods (and wood margins and grassland) on mesic fairly nutrient-rich and base-rich, mostly lime-poor, neutral to slightly acid, humus-rich, deep clay and loam soils. In Berkshire, Druce (1897) found it associated with Colchicum autumnale, Lathyrus sylvestris, Polygonatum multiflorum and Vicia sylvatica in Ashridge Wood (Grid Ref. SU500784) where it still occurs under ash-maple woodland with hazel and oak standards (English Nature SSSI Notification 1983). In the Caucasus and Crimea, it occurs on the steppes and on arable land in field crops (Komarov 1968). In France, it is local and occurs in ash-hornbeam woods and in meadows (Guinochet & de Vilmorin 1978). In Germany, Austria and Switzerland it occurs in scattered sites in meadows, scrub and in hedges (Hegi Fl. ed. 1, 2, pp. 319–320). In Switzerland, most of the sites are beech forest on calcareous soils (Keller 1991). Further east and in Turkey, it, or a very similar species, appears to be much more common (Davis 1984). In woodlands and hedgerows, competition with deciduous trees and shrubs for light is avoided by early leaf emergence (January) and growth to April/May. Competition with other herbs is avoided by long leaf length (400–500 mm in woodland and 730 ± 110 mm (n = 7) in hedges) and up to 1 m scape length. In open grassland at Eaton Socon, scape length is shorter (505 ± 134 mm, n = 13, 21 May 1990). In thick stands of some species (e.g. Allium ursinum and Mercurialis perennis) in woodland, O. pyrenaicum appears to grow less vigorously, but more vigorously in mixed stands of Hedera helix, Hyacinthoides nonscripta and M. perennis. With roots growing from the base of the bulb downwards, intense competition with many shallower-rooted plants such as M. perennis and most grasses may be avoided. Indeed, it can compete with other plants in the open grassland in the absence of grazing. Although O. pyrenaicum occurs abundantly in sizable populations, it does not form almost monospecific stands characteristic of Hyacinthoides nonscripta but grows with other plants both in woods and hedges. The populations are usually present in fairly uniform, large patches (more than 10 m2) with mature plants about 25 cm apart (mean nearest neighbour distance 24 ± 15 cm, n = 38, Slittems Wood, Wiltshire, 6 February 1990), although occasionally they are found in smaller groups ranging from 1–10 m2 (e.g. Englishcombe, Somerset). Flowering in many, if not most, years shows patchiness. The density of plants varies considerably. In Slittems Wood (Wiltshire), 20–40 m-2 (in 1990 and 1998) were recorded compared with a density in Englishcombe Wood (Somerset) of about 8 m-2 (in 1990 and 1998) at its greatest, and about 36 m-2 (in 1990) on a roadside at Eaton Socon (Bedfordshire). These counts (especially at Slittems and Eaton Socon) include a significant number of small young plants and seedlings (up to about 50% of the population) all of which would not be expected to survive to maturity. In Saarland, Germany, it occurs in low densities up to 10 m-2 and, in 1980, a very much smaller isolated population was estimated at only 2000 plants in an area 100 × 200 m (Wetter 1981). The main habitats are woodland, hedgerow and roadsides, which have widely ranging conditions. The height of leaves is variable, depending on available light in the habitat and competition with other plants (see Section IV). The rate of elongation of leaves is constant throughout the growing period from January to May and keeps up with surrounding plants; this growth allows them to reach up to 1 m in tall herbage by hedgerows. Plants displayed similar performance in woodlands in the Bath area and in open grassland near Eaton Socon, Bedfordshire. Plant density, number of leaves per bulb, bulb volume, the probability of mature bulbs flowering and capsule size were found to be all similar in the two types of habitat. However, the number of scales in the bulb was fewer in the roadside habitat and the mean number of capsules per scape was higher in the open (Table 3). Even in the open, only about 40% of the flowers produce capsules, indicating that shading alone does not limit the number of capsules. Although hedgerow plants produced more seed per capsule, woodland seed was approximately 10% heavier (6.3 mg) than hedgerow seed (5.7 mg) (t-test, P < 0.005, n = 22 for each sample of 10 seeds). In an experiment with different soil types, plants in Keuper marl had a greater success in establishing from seed than those in other soils (Table 4), indicating that soil type could be an important determinant at this stage in the life-cycle. This plant seems little affected by extremes in climate experienced in Britain. For example, the summer of 1989 was exceptionally warm and dry, resulting in the most severe drought in the O. pyrenaicum sites since 1976 but, as most of the growth took place before the onset of drought, little effect was observed. The young leaves are apparently frost resistant as they are unaffected by frosts in February and March. Although the leaves are much longer than those of many other bulbous geophytes, they may be distinguished by the distinctive channel on the upper surface, the narrowness compared with length and the glaucousness. When emerging from the soil, the leaves tend to fold together into a single structure enabling penetration through leaf litter (Salisbury 1916; Sydes & Grime 1981a,b). Stomatal density: 42 ± 4 mm-2 (n = 6) (similar on both abaxial and adaxial surfaces) and the stomatal index (Cutter 1969) is 0.40 ± 0.05 (mean ± SD, n = 18 with total of 1317 epidermal cells counted). Adaxial (0.42 ± 0.05) and abaxial (0.38 ± 0.05) surfaces were not significantly different (t-test, P = 0.072). The mature bulb is approximately 20 mm high and with a volume of 13.1 ± 3.9 cm3 (mean ± SD, n = 15) at the flowering stage. The roots are unbranched, white and 1–2 mm thick and there are possibly 30–40 roots per bulb (for example, two bulbs carefully dug up in September 1989 and September 1988 and cleaned of soil had 36 roots 40–150 mm long and 40 roots of mean length 100 mm, respectively). The contractile roots are thicker and narrowly spindle-shaped. Roots emerge from the rim of the 'button' or stem at the base of the bulb. There are 31.5 ± 3.4 fleshy scales (mean ± SD, n = 15) in the mature bulb, which include the bases of leaves of previous years. In addition, the basal remains of the previous scapes persist between the scales. As the bulb scales are formed from leaves produced over 3–4 years, dissection of the bulb to find the age of the scales and the number of scape bases reveals the frequency of flowering over this period. Of the outer scales, 3–5 are scarious, a pale brownish colour and often decomposing. There are usually about seven leaves in mature bulbs; the number of leaves on each plant is discussed later. Mycorrhizal infections were not detected using the method of Phillips & Hayman (1970) in roots of plants collected from three locations (Slittems Wood, Wellow and Englishcombe) in December, February and April (respectively), although other associations with fungi were occasionally observed, which may account for the single report in the literature of infection in this species (Harley & Harley 1987). Geophyte. Perennation commences with the death of the flowering spike and seed ripening in July, the leaves having senesced two months earlier. Between then and the appearance of new leaves in January, a few plants may be located by the persistent dead flowering stems. The bulb contains unexpanded leaves and possibly a terminal flowering spike. Soil features can determine the bulb depth. The bulb may be 100–130 mm deep (to its base) but can be shallower. Indeed, bulbs have been found almost at the surface with a stone beneath them apparently preventing their descent. Vegetative reproduction appears to be possible as various stages of bulb division have been noted. Large clumps are not formed; however, up to four or possibly more tufts of leaves have been found forming one clump and this is probably a result of vegetative division. For example, in Slittems Wood, of 403 plants only 6.5% were doubles, 2.0% triples, 1.0% quadruples and one sextuplet was found, although the possibility of juxtaposed plants arising by chance from seed could not be discounted. At Eaton Socon, of 169 plants, 4.4% were doubles, one was triple and two were quadruple. Soil movement or disturbance causes the only vegetative spread possible by, for example, animals. Although bulbs were not infrequently observed brought to the surface by animals digging or trees being uprooted, distances moved were small and bulbs left on the surface are likely to dry up. Mature bulbs can form numerous contractile roots which would draw them back down. Small bulbils, which possibly contribute to vegetative reproduction, develop occasionally at the side of the base of the bulbs. Vegetative reproduction is less significant than reproduction by seed and Wetter (1981) also concluded that it was an unimportant means of reproduction in Saarland, Germany, as lateral bulbils were usually absent. There is one spike per bulb but bulbs do not always flower. First flowering can occur at the five-leaf stage although most flowering bulbs have more (up to 10) leaves. Bulb dissection indicated that the frequency of flowering in previous years was also positively correlated with the number of leaves, bulb volume or number of bulb scales but most closely to the diameter of the 'button' (stem) at the base of the bulb. As roots are formed from the perimeter of the button, it can be deduced that bulbs flowering more frequently would have more roots. As the roots do not branch, root number would determine the extent of soil exploitation, which could be important for supplying nutrients for productivity, and hence flowering and seed production. Longevity of individual plants is not known. Twenty pegs were used to mark plants in 1990. By 1998, only six pegs remained but none of these marked plants was present in 1998. Observations on the number of individuals in size categories (leaf number and bulb size) of plants in samples of the community suggest the life-span is over 5 years. Young plants with one leaf, putative seedlings, are also present each year. As populations contain a large number of young plants (< 5 leaves) located away from established plants, reproduction by seed is regarded (as indicated above) as the normal means of recruitment. In Slittems Wood and at Eaton Socon, the majority of the plants had 5–6 leaves and 1–2 leaves (putative seedlings), with fewer plants with 3–4 leaves. This pattern may result from high mortality of young plants (< 4 leaves) superimposed on an accumulation of mature plants (4–9 leaves). With about one leaf added per year in young plants (as indicated by plants marked from the previous year), it may take 5 years for a plant to flower. Similar patterns were observed in well-established populations of H. nonscripta and Leucojum vernum. The diploid chromosome number is 2n = 16 for material collected from 70 stations over most of Europe (Wittman 1985). Although Wittman did not include England, other reports agree with this number (including material from Slittems Wood confirmed by Dr C. Grant). Wittman (1985) gives karyograms of material from Saint-Logis, France, and Magasa, Italy, whilst Pastor & Diosdado (1994) do so from material from Andalusia (western Spain). None. None. Seasonal variation in appearance of the leaves in spring is very great. Leaf growth may start in January in mild winters but later in more severe ones. It proceeds almost linearly with time as observed from mid-February to late-April in 1988 (Fig. 3) despite the seasonal rise in temperature and the leaves continued to elongate whilst senescing at their distal ends. As in many bulbous species, flowers are formed in the year before flowering and the scape elongates after the leaves in spring, with the scape still being in the bulb in April. An unusual feature is that flowering does not usually commence until after the leaves have died. Flower opening occurs from late-May to early-June after scape elongation and is from the bottom of the raceme but does not fully extend to the top where undeveloped buds on the spike wither. Root growth is difficult to measure in the field but can be seen in excavated bulbs as early as the end of June. A dense inflorescence of buds, which is collected for eating ('Bath Asparagus'), develops at the top of the elongated scape, because the inflorescence axis between the flower buds does not elongate until after the flowers open. Growth of leaves of Ornithogalum pyrenaicum in spring (1988). In the bud, a stamen fits exactly into each tepal but as the bud unfolds the tepals elongate, bending outwards at right angles to the stamens, which are left almost vertical. The stamens are longer than the stigma initially but loose pollen is present when they become the same length. The anther turns to become at right angles to the filament and the stamens bend outwards until the anther is level with the top of the ovary. The six stamens dehisce in two successive groups of three. As the flower fades the tepals enclose the ovary. Pollinators such as bumble bees (e.g. Bombus terrestris) and honey bees (Apis mellifera) and occasionally butterflies (e.g. meadow brown butterfly, Maniola jurtina) visit the open spikes but other insects such as flies and beetles are also attracted by the flowers but may not be involved in pollination. Quantitative observations of pollination indicated that the prime pollinators were bees (Table 5). They were attracted to the spikes probably by sight; after alighting on the spikes they worked round them, collecting pollen and nectar (some individuals solely nectar and some both), the body of the bee passing over the stigma while probing for nectar. A bee visited several flowers before moving to another spike, alighting on about four spikes per visit to a group of 14 plants. Within 1 hour, a mean of five visits per plant was made, giving good opportunity for cross-pollination. On this basis, a spike flowering for 2 weeks could be visited up to, or even over, 1000 times. Unlike the bees, the flies were not seen to pollinate the flowers. In Saarland, Germany, pollination was carried out in warm sunny weather by flies, bees and bumblebees (Wetter 1981). None recorded in Britain. Floral abortion in the upper half of the inflorescence in June began with the yellowing of pedicels and before the terminal flowers opened. This was in addition to the withering of the unopened buds at the top of the inflorescence. At Eaton Socon, this resulted in only 40% (14.0 ± 4.1) of the flowers forming capsules because 10% (3.2 ± 3.2) of flowers had not set at the base of the inflorescence and 50% (17.6 ± 4.6) had not set above or had aborted before opening. As the inflorescence bore many fewer capsules than the number of opened flowers and only the lowermost flowers formed capsules, floral abortion appeared to be a consequence of how many developing capsules the plant could support, rather than a lack of pollination. Eventually all capsules mature at about the same time in August. The number of seeds in the capsules varies, with l8 (6 per carpel) representing a well-filled head. Some carpels contain 8 seeds, but of these at least two are likely to be very small. The capsules containing most seed tend to be at the bottom of the raceme but the number of capsules per plant is very variable. During development the pedicels turn from horizontal to nearly vertical. When the seeds are ripe (in August in the open and September in shade), the valves of the capsules diverge partially and the seeds are dispersed over a long period (some still being present in the capsule in late October). When the uppermost seeds have dispersed the others become slightly concave on one side, which may help their escape from the capsule. The seeds fall to the ground when the plant is moved by wind. As the seed is relatively heavy, wind dispersal would be quite restricted but seed may be carried further by vectors (because of their size possibly ants) removing them from vegetation and the soil surface. In germination tests carried out in pots, the majority of seedlings emerged in late-February but a few were still appearing in late March and early April. Up to about 80% germination was recorded with the majority surviving to form bulbs at the end of the season (Table 4). The seed does not appear to require low temperatures to germinate. Germination is epigeal and the seed remains attached to the tip of the first leaf which maintains a bend 20–30 mm below the lead tip but straightens when mature (Fig. 4). The seedling appears above ground as a single glaucous terete narrow leaf 1–2 mm wide and becoming 100–150 mm long. The bulb formed is narrowly cylindrical or oval, 20–30 mm long, 2–4 mm in diameter and pointed at the apex. After the second year the bulb has increased more in diameter than in length. Drawings of seedlings of Ornithogalum pyrenaicum. (a) seedlings after germination (4 February 1989); (b) seedling 32 days later; (c) seedling 42 days later still; (d) young plant at same date as (c) but grown from seed the previous year; (e) mature plant in early spring (14 February 1988); (f) 1-year-old plant (14 April 1989) showing position of the bulb relative to a mature bulb. Most of the seeds germinate within 1 year of being shed to produce one-leafed seedlings in the following spring. At the end of the first season, 1-year-old bulbs are still small. For example, in 1989, 1-year-old plants produced bulbs of 18.3 ± 5.5 mg (n = 6) dry weight from seed of 5.3 ± 0.5 mg dry wt, indicating only a 3–4 fold increase in dry matter in the first year. The seedlings found growing were in open spaces, often amongst Hedera helix. The seedlings died back earlier than the mature plants under natural conditions. Young plants (1 and 2 year old) have a single contractile root that pulls them down towards the depth of the mature bulb. Marked plants in Slittems Wood selected as having 1–4 leaves in 1990 (mean 2.5 ± 1.0) increased on average with 0.6 additional leaves in 1991 (mean 3.1 ± 1.4, n = 12, P < 0.05). Mature plants with 5–8 leaves in 1990 (mean 6.3 ± 1.2, n = 10, P < 0.05) also increased to a mean of 7.1 ± 1.2 in 1991. As flowering did not start before the five-leaved stage, the minimum age from seed to maturity can be estimated at 5–10 years. In the Bath area, mollusc (especially slug) damage was commonly observed but timing and amount varied. Horses do not eat O. pyrenaicum (J. Aldridge, personal communication) but cows and sheep were observed to graze the leaves and spikes indiscriminately. Both Puccinia hordei Otth and P. liliacearum Duby (Ellis & Ellis 1997; C.M.I. Herb., personal communication) are reported to infect O. pyrenaicum. The frequency of occurrence of P. hordei (identified by Dr M.F. Madelin) was found to be very variable in the Bath area; for example, in 1989 in most localities some infection was observed with about 50% of the plants in Slittems Wood being infected on 19 March, although by 30 April the symptoms were less prevalent. Wilson & Henderson (1966) state that P. hordei can weaken the host (Ornithogalum spp.) impairing flowering. Local people have picked flower buds for eating ('Bath Asparagus') after the scape has elongated before the first flower at the base of the inflorescence opens. In some years recently, nearly all the flowers disappeared by, for example, 26 May 1988 at the Uplands site and, by 4 June 1988 when the first flower opened in Slittems Wood, in an open area, about 75% of buds had been removed (but it was not known by whom or what), especially in thick areas of Hedera helix or Mercurialis perennis where access was unimpeded. Flowers on spikes appearing in the middle of bramble beds, or the occasional scattered individual, often remained and flowered normally. In Wiltshire and Somerset, the plant has been known since the 16th century (Ray 1724), in Bedfordshire near Eaton Socon since the 18th century (Dony 1953), and for more than a century in Berkshire in woodland (Ashridge Wood) on the chalk (Druce 1897). Although there do not appear to be any reports of pollen from postglacial deposits, the plant is generally regarded as native since the last Ice Age. In Britain, Johnson (1634) first recorded O. pyrenaicum: 'Ornithogalum angustifolium majus floribus ex albo virescentibus Bauhin…It grows in the way between Bath and Bradford not farre from Little Ashley'. It was further recorded by Ray (1724) in the Bath area and again by Lightfoot in 1773 at a site between Keynsham and Bristol at or close to a 1988 record. It has been suggested that it may have been introduced by the Romans (Green 1993). The young flowering spikes were collected and eaten (Collinson 1791) and sold in Bath market (Murray 1896 (in White 1912); Roe 1981). Although now no longer sold, it was regularly eaten until comparatively recently at least up to about 1939 (verbal communication from two Keynsham residents) and is reported to be served even now in some local restaurants. There is no immediate conservation danger of losing the populations of O. pyrenaicum in England although the Bedfordshire site has one of the smallest and is potentially at greater risk, as may be the populations in Berkshire. Removal of flower buds in the Bath area could be a significant threat in some areas but its demographic effect on the populations is not known. Of the thousands of plants seen at Slittems Wood, Wiltshire, in April 1990, fewer than 20 bearing seed heads were found later in the summer owing to picking. If 40% of mature bulbs flower each year, this level of harvesting may not allow an acceptable seed production to sustain the population. However, in Slittems Wood recruitment of young plants to the population in 1990 and 1998 was at a similar level. In 1998, the proportion of young plants and overall density of plants had increased. In contrast, there was low recruitment in Englishcombe in 1990 and in 1998 but the density of plants remained constant. We thank Dr M.H. Martin and Professor A.J. Willis for their kind assistance with the preparation of the manuscript, Dr A.J.C. Malloch for quadrat and NVC data, Mrs J.M. Croft for the preparation of the British distribution map, and Glyn Woods for the European distribution map.