A cormous perennial of acidic, brown-earth soils, found on grass-heaths, usually in association with Pteridium which may afford the plant some protection from grazing. It reproduces primarily by offsets, as flowering and seed production appear to be limited. Lowland.
First recorded in the wild in 1856, there has been little recent change in the overall distribution of this species, but populations have declined locally, probably as a result of recent changes in management such as Pteridium control and excessive or poorly managed burning.
Mediterranean-Atlantic element. Our plant may be an endemic subspecies.
Count of 10km squares in Great Britain: 9
Count of 10km squares in Ireland: 0
Count of 10km squares in the Channel Isles: 0
Atlas Change Index: -0.1
External Species Accounts
RDB Species Accounts
Gladiolus illyricus Koch (Iridaceae)
Status in Britain: LOWER RISK - Near Threatened. WCA Schedule 8.
Status in Europe: Not threatened. Endemic.
G. illyricus grows in bracken-dominated acid grass heaths, generally on unpodsolized and stoneless brown earths. It may occur under a canopy of Pteridium aquilinum with few other associates, or in a more grassy sward in which prominent species may include Agrostis curtisii, Conopodium majus, Galium saxatile, Genista anglica, Polygala serpyllifolia, Potentilla erecta and Veronica officinalis. Two constant associates are Hyacinthoides non-scripta and Anemone nemorosa, and stands of Ulex europaeus are typically found in the vicinity.
It is a perennial, flowering between June and August. Flowers are visited, and presumably pollinated by bees and butterflies, particularly the Large Skipper. Each capsule generally contains 16-21 seeds, which usually fall within one metre of the parent. A study of a small population in 1987 (Stokes 1987) showed that only 2% of the plants developed flowers and set seed. If this is the general picture, then most recruitment is likely to be by vegetative reproduction, i.e. the formation of cormlets within the corm scales, with wider establishment from seed a rarer event.
G. illyricus was first discovered in Britain by the Reverend W.H.Lucas in 1856. Babington (1863) regarded it as truly native in Britain, but Townsend (1904) suggested that G. illyricus may have arrived with Erica vagans and Simethis bicolor on the coast near Bournemouth with young fir trees from Landes in France, and subsequently spread into the New Forest. It is now widespread, though local, in the New Forest, with recent records from about 40 1 km squares in six hectads. Populations differ greatly in size, some comprising few plants, whilst others have several thousands. It formerly occurred, as a possible native, on the Isle of Wight, and introduced populations have occasionally been reported elsewhere.
In recent years, a considerable decline in numbers has been apparent at some sites. Factors in this decline include the encroachment of scrub and heather, attempts to eradicate bracken, and indiscriminate heath-burning (Brewis, et al. 1996). Intense grazing, particularly by deer and horses (but also by rabbits, cows and molluscs), is often evident. However, since large herbivores do not graze in dense bracken stands, grazing pressure tends to be much less severe in summer, thereby allowing the full development of G. illyricus growing under it. The bracken canopy is frequently damaged by spring frosts, leading to years of varying bracken density. In 'open' years, the increased light enables the corms of G. illyricus to increase in size, thus promoting flowering in subsequent seasons. Furthermore, the greater opportunities for insect pollination may lead to a higher proportion of seed being set. However, in such 'open' years, grazing increases, as also does competition from other plants. Conversely, in years of dense bracken, much reduced light levels may lead to increased mortality. Mature plants may become choked by bracken litter, and fewer seeds germinate because of the production of bracken toxins, though grazing and competition from other plants decrease. Thus, both 'open' and 'closed' bracken canopies have advantages and disadvantages, and an alternation in bracken density may provide the most ideal conditions for populations of G. illyricus.
It is widespread in Europe, particularly in the south and west, extending eastwards to Bulgaria and Greece. In continental Europe, it is found in a much wider range of habitats, including heaths, scrub, open woodland, and calcareous coastal cliffs.
Some authorities consider that G. illyricus in Britain is sufficiently different from populations in continental Europe to warrant its recognition as the separate ssp. britannicus (A.P.Hamilton, pers. comm.) This proposal is based on genetic and floral differences. In the British populations 2n = 90, whilst in continental Europe 2n = 60. The only populations matching those in Britain occurred on Belle Isle in Brittany, but they were destroyed recently during the construction of a dam, though herbarium specimens from Belle Isle are held at Kew.
PLANTATT - Attributes of British and Irish plants. (.zip 1455KB) This dataset was compiled and published in 2004, and last updated in November 2008. Download includes an Excel spreadsheet of the attributes, and a PDF explaining the background and nomenclature. Note that the PDF version is the booklet as published, whereas the Excel spreadsheet incorporates subsequent corrections. A hardcopy can be purchased from the Centre for Ecology and Hydrology.