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Leontodon saxatilis Lam., Lesser Hawkbit (= L. taraxacoides (Vill.) Mérat nom. illeg.)

Account Summary

Native, occasional. Suboceanic southern-temperate; adventive in Fennoscandia and introduced in N & S America and New Zealand.

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

July to October.

Fermanagh Occurence

Growth form, identification and preferred habitats

A rather slender, wintergreen, usually short-lived perennial, or rarely a biennial species, with a short, erect, truncate (ie premorse) rootstock and rather fleshy roots, L. saxatilis resembles a smaller form of L. hispidus (Rough Hawkbit), both these differing from the much more common L. autumnalis (Autumn Hawkbit) in having a number of unbranched flower stems. The stems grow 5-40 cm tall and there are at least some ciliate, branched hairs (ie hairs forked at the tip) on the leaves of the basal rosette which are oblanceolate in shape and vary from almost entire to sinuately toothed, to deeply and irregularly pinnately lobed, the blade gradually tapering into the long, stalk-like base (Hutchinson 1972; Clapham et al. 1987; Stace 2010).

L. saxatilis can be usually recognised by examining the underside of the outer strap-shaped florets, which are typically striped grey or violet in colour (reddish in the other two species). Unfortunately, this feature has not been found to be 100% reliable. It is therefore best to examine the appearance of the pappus attached to the fruiting achenes (Silverside 1990b). In L. hispidus, the pappus hairs form a double ring, the hairs of the outer ring being shorter and toothed, rather than branched. In L. saxatilis, the outermost row of achenes differ from the rest. Instead of a pappus of brownish-white, branched hairs, the outer achenes possess a crown-like ring of pale scales which are easily seen with a × 10 lens (see Flowering reproduction section below).

L. saxatilis is mainly a plant of dry, basic lowland soils and sand dunes and it tolerates regular disturbance in open habitats, such as on driveways and in car parks. In lawns, it survives mowing and trampling and, in pastures, it is persistent and can cope with moderate grazing pressure. Although usually found in short, open turf and colonising bare patches in rough grassland or heathland over dry to damp, well-drained, basic or calcareous soils, it can tolerate ground that is moderately acidic and not necessarily calcareous, and that periodically or temporarily floods, such as along rutted tracks, or other kinds of fairly wet areas near lake or pond shorelines. It cannot tolerate shade, but it does behave as a pioneer colonist of stony banks and rock outcrops, particularly of basic or calcareous geology, and it is found in quarries and along tracksides on shallow, often rocky, soils. Towards the north of its B & I range it tends to be restricted to sand-dune habitats (Sinker et al. 1983).

The established strategy of L. saxatilis is categorised as SR/CSR, meaning it is intermediate between a Stress-tolerant Ruderal and a more balanced mixture of all three basic strategies, Competitor, Stress-tolerator and purely Ruderal (Grime et al. 1988, 2007).

Flowering reproduction

L. saxatilis relies on seed for its increase and spread. The small rosette plant produces just a single flower-head or capitulum on one to several leafless stems or scapes, up to 30 cm tall, arising from the centre of the basal leaf rosette. Each solitary capitula is around 12-20 mm in diameter, with several rows of phyllaries that are lanceolate, acute, sparsely or very hairy and imbricate (ie overlapping like roof tiles). The capitula are drooping when in bud (Clapham et al. 1987). As in the Dandelion (Taraxacum spp.), all the florets are strap-shaped (ie ligulate), 8-14 mm long, pale or golden yellow, the outer ones purplish or greyish-violet striped beneath.

All the florets are bisexual and the style is hairy. As is always the case, the flowers are protandrous and pollination is by numerous kinds of bees and syrpids that visit and are presented with a small amount of pollen by the retracting stamens and their anther tube as the insect proboscis probes and seeks out the well-concealed nectar at the base of the floret. Later, when the pollen is more or less exhausted, the hairy style elongates past the anther tube, picking up any remaining pollen, and the bilobed stigma then opens up and displays its receptive upper surfaces to visiting insects. Self-incompatibility is almost certainly involved in what is essentially an out-breeding mechanism (Butcher 1961; Hutchinson 1972; Proctor & Yeo 1973; Sell & Murrell 2006).

The achene fruits are of two kinds, the ones of the outer row being 3-4 mm long, pale brown, ± cylindrical, curved, faintly transversely wrinkled (ie almost smooth), longitudinal ribs, each achene surmounted by a cup of small, scarious scales replacing the pappus. The inner achenes are c 5 mm, fusiform (ie tapering at both ends), ± shortly-beaked, chestnut brown, straight, with strongly muricate longitudinal ribs (ie the ribs rough with short firm projections), and topped by a brownish-white pappus of feathery hairs (Butcher 1961; Clapham et al. 1987; Sell & Murrell 2006).

The current author (RSF) has not managed to locate any statistics regarding seed production or dispersal distances achieved by plumed achenes but, presumably, in common with similar species, wind dispersal provides movement of around a few metres from the parent plant.

The survey of soil seed banks in NW Europe contains six estimates of L. saxatilis seed longevity, two transitory (less than one year), two short-term persistent (survive at least one year, but less than five), and two present in soil, but not assigned regarding length of survival (Thompson et al. 1997). Germination appears to be mainly in the spring and early summer following seed production (Fitter 1987).

Irish occurrence

Lesser (or Hairy Hawkbit) is much less local in Ireland than Leontodon hispidus (Rough Hawkbit), for which there are no Fermanagh records. While Lesser Hawkbit has been recorded at least once in every Irish VC and it is very frequently found in the S & C of the island, it remains rare throughout the N of Ireland (Cen Cat Fl Ir 2; An Irish Flora 1996). Harron (Flora of Lough Neagh) found L. saxatilis was locally frequent all round Lough Neagh on waysides, waste places and gravel workings near the lough shore.

Fermanagh occurrernce: In Fermanagh, Lesser Hawkbit is occasional and has been recorded in a total of 29 tetrads, although only 20 of them have post-1975 records. It occurs in dry, well-drained, sandy or gravelly pastures and in open ground on lakeshores, quarries and stony roadside banks, especially on basic or base-rich soils. As the tetrad distribution map indicates, it is very thinly scattered around Lough Erne and also on the marl soils along the River Finn valley in the SE of the county.

British occurrence

In Britain, L. saxatilis is frequent and widespread in the south, but it becomes rare and coastal further north into Scotland. It has also declined considerably in C & N England since the 1950s. Overall, thanks probably to the two editions of the BSBI Plant Crib (1988, 1998), this species is more readily distinguished from the other two B & I Leontodon species than earlier Flora keys allowed and, consequently, the recording of it, as displayed in the New Atlas and the Atlas 2020, is much better than that plotted in the previous BSBI Atlas (Perring & Walters 1962; F.H. Perring, in: Preston et al. 2002; F.H. Perring and K.J. Walker, in: Stroh et al. 2023).

European and world occurrence

L. saxatilis belongs to the Suboceanic southern-temperate phytogeographical element and is mainly found in W & SW Europe. It is an 'adventive' species further north in Scandinavia (ie an introduction, but not fully established and self-sustaining; it is derived from the Latin 'advenire', meaning 'to arrive' (Holmes 1979)). In the south of its range, the species is rare or very rare in the Mediterranean basin. It has been recorded, however, in the Azores, Mallorca, Madeira and the Canary Isles (Beckett 1993; Press & Short 1994; Schäfer 2002). It is introduced very sparsely into N & S America and also, more frequently, into New Zealand (Hultén & Fries 1986, Map 1885; Webb et al. 1988). In view of the mobility displayed by the species, it has to be speculated that seed has travelled with man, most likely as an impurity of agricultural grass mixtures in the years previous to modern seed cleaning methods.

Names

The genus name 'Leontodon' is a combination made by the Swedish botanist Linnaeus of two Greek words, 'leon' meaning 'lion' and 'odous' meaning 'tooth', an allusion to the toothed leaves of the 'Dandelion' from the French, 'Dent de lion', our Taraxacum officinale, which Linnaeus included in his genus Leontodon (Gilbert-Carter 1964). The Latin specific epithet 'saxatilis' is from 'saxum', meaning 'rock' and suggests 'growing on or among rocks', or 'found among rocks' (Gilbert-Carter 1964; Stearn 1992), only one of the many habitats occupied by the species. The previous Latin specific epithet, now superseded, 'taraxacoides', means 'like Taraxacum', or 'like dandelion' (Gledhill 1985), presumably a reference to the entirely ligulate florets in the capitulum.

The English common name 'Hawkbit' is derived along with 'Hawkweed' (Hieracium), since the plants were for a long time confused with other yellow members of the family Asteraceae, from the Greek, 'heiras' meaning, 'hawk', referring to the ancient belief reported by Pliny (Book lxx, c. 7), "because hawks tear it apart and wet their eyes with the juice, so dispelling dimness of sight, when it comes on them" (Prior 1879). Apart from 'Lesser Hawkbit', referring to the smaller size of the plant compared with both L. autumnalis and L. hispidus, the species has been called 'Hairy Hawkbit', 'Hairy-headed Hawkbit' and 'Rough Hawkbit' in various Floras.

Threats

None.

References

Webb,D.A., Parnell,J. and Doogue,D. (1996); Scannell, M.J.P. and Synnott,D.M. (1987); Harron, J. (1986); Silverside, A.J. (1990b); Plant Crib (1988 & 1998); New Atlas; Perring & Walters (1962, 1976); Stroh et al. 2023; Hultén & Fries 1986; Butcher 1961; Hutchinson 1972; Sell & Murrell 2006; Clapham et al. 1987; Proctor & Yeo 1973; Grime et al. 1988, 2007; Thompson et al. 1997; Webb et al. 1988; Gilbert-Carter 1964; Stearn 1992; Gledhill 1985; Holmes 1979; Schäfer 2002; Beckett 1993; Press & Short 1994; Stace 2010; Sinker et al. 1983; Fitter 1987; Prior 1879