Crepis vesicaria L., Beaked Hawk's-beard

Account Summary

Growth form and identification

An annual or biennial rosette herb, usually moderately robust, up to 80 cm tall and roughly hairy (Silverside 1990). It has a rather stout taproot and generally develops several stout branches from just above the basal leaf rosette, or it may often produce a solitary, more leafy main stem. The flat-topped inflorescence of C. vesicaria consists of numerous small dandelion-like heads, 15-40 mm in diameter, arranged in a corymb. The outer florets of the flowerheads are striped reddish brown beneath, which makes a useful distinguishing feature from C. biennis (Rough Hawk's-beard).

C. vesicaria, Beaked Hawk's-beard, is so called on account of the long, narrow beak on the achene at the top below the pappus. The beak is as long as the fruit itself and it is the ultimate distinguishing characteristic of the species (Perring & Walters 1989; Silverside 1990). Another useful feature that helps separate C. vesicaria from C. biennis is that it flowers at least a month earlier than the latter. As a consequence of the long beak, the pappus parachute of 50-60 silky-white hairs extends beyond the surrounding bracts (Salisbury 1964). In the absence of mature achenes, C. vesicaria is best distinguished from large forms of the very common C. capillaris (Smooth Hawk's-beard), with which it is commonly confused, by the silky haired inner surfaces of the inner involucral bracts (similar to those of C. biennis – see the species account of the latter for the distinguishing characters of these two species).

Salisbury (1964) estimated the mean annual achene production at around 7,000 per plant. Typical habitats include roadsides, waste ground and railway embankments and there is a preference for lime-rich soils (Salisbury 1964; Silverside 1990).

British occurrence

A native of southern Europe, SW Asia and NW Africa, C. vesicaria is an established alien only in the more continental part of Britain, south of a line from the Wash to the Humber. Elsewhere in B & I, it is a rare colonist or casual species, although it is definitely spreading northwards (BSBI Atlas 2; New Atlas; Atlas 2020). Generally behaving as a biennial, it was first recorded in Britain in 1713, but it remained uncommon until the last few decades of the 19th century. It then began to spread rapidly northwards to become established in England, Wales and then, eventually, in Ireland (Perring & Walters 1989; Clement & Foster 1994).

Irish occurrence

In Ireland, the plant grows mainly in the E & C of the island. It is, for example, abundant on dry banks, roadsides and waste ground, usually in urban and suburban areas of Co Dublin (H21) (Flora of Co Dublin), but it is only very rarely recorded in more northern counties of the island. FNEI 3 lists just four records for the three NE counties, dating from 1972-86. There are three coastal sites in Co Down (H38) and a solitary one in Co Antrim (H39).

Fermanagh occurrence

In Fermanagh, there has only ever been the solitary record listed above. The railway station where Praeger found the species is defunct, since the lines closed in 1957, but it is typical of the sort of dry, disturbed habitat frequented by this introduction throughout B & I. The relatively sharp northern and western cut-off observed in the B & I distribution of this essentially Mediterranean species strongly suggests an effective climatic limit has been reached, preventing its further spread (New Atlas).

Names

The Latin species epithet 'vesicaria' means 'inflated, bladder-like', but it is not immediately apparent to what characteristic of the plant this refers.

Threats

None.

References

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