Linaria purpurea (L.) Mill., Purple Toadflax
Account Summary
Introduction, neophyte, garden escape, very rare.
July 1990; Northridge, R.H.; on a wall in Pettigo village.
Growth form and preferred habitats
An erect, tufted, colourful, attractive perennial, native of C & S Italy and Sicily, Purple Toadflax has been commonly grown in gardens in B & I from sometime before 1648 and remains a popular decorative subject with several named cultivars, including a common pink flowered one, cv. 'Canon J. Went' and a rarer white one, cv. 'Springside White' (Griffiths 1994; Buczacki 2007). It was first recorded naturalised outside a garden setting in the wild in Middlesex around 1830 and its frequency and distribution in Britain, at least, has greatly increased in the 40 years between the two BSBI Atlases (Perring & Walters 1962; Preston et al. 2002).
The plant has a glabrous stem, 40-120 cm tall, often branched above, bearing numerous, glabrous, linear-lanceolate leaves up to 4.5 cm long, the lower ones whorled. The nectar spur on the flowers of both L. purpurea and L. repens (Pale Toadflax) is curved. L. repens differs from L. purpurea in having whitish, purple-striped flowers and a less dense inflorescence (Garrard & Streeter 1983).
Purple Toadflax most commonly grows on old walls, dry hedge banks and stony waste ground along roads and in urban pavement and less disturbed ground around railways and quarries (Garrard & Streeter 1983; A. Horsfall, in: Preston et al. 2002). In all its habitat types, it demonstrates both great ability to tolerate stress and an obvious avoidance of biological competition.
Flowering reproduction
Flowering takes place from June to August, the flowers, 6-8 mm long, being borne in long, dense, leafless, spire-like racemes with bracts equalling the flower stalks. On each flower, the five calyx teeth are linear-lanceolate, acute and longer than the tube. The corolla is lilac-purple to purplish-violet, irregular, 2-lipped, personate, and the long, curved spur is about 5 mm long, as long as or longer than the petal limb. The stamens are four in number and are included within the corolla tube. The pale purplish style on the globular, superior ovary is single and has a small, green, capitate stigma. The flowers are very attractive to bees that pollinate them and they are self-incompatible (Sell & Murrell 2007; Stace & Crawley 2015). When fertilised, the ovoid capsule is much longer than the sepals and it opens with 3-triangular teeth on each of the two cells. The ovoid seeds are 1.3 × 1.0 mm, angled, deeply honeycombed and brown in colour (Butcher 1961; Streeter et al. 2009).
L. purpurea seeds freely and prolifically in a garden setting, spreading into paving, gravel, walls and any open ground, so that it can soon become an over-abundant, weedy pest (Stace & Crawley 2015).
Fermanagh occurrence
There are just three records in the Fermanagh Flora Database, all found by RHN from 1990 onwards. They are from perfectly typical habitats of the species in these islands, ie walls and dry stony waste ground where they are definite garden escapes or discards. The remaining record details are: stony ground at Lisbellaw village, July 1994; and on pavement at Windmill Heights, Enniskillen town, May 2001.
British and Irish occurrence
L. purpurea naturalises itself widely in these islands and can become established. Previously it had been listed as occurring at least once from eleven Irish VCs (Cen Cat Fl Ir 2; FNEI 3), but Reynolds (Cat Alien Pl Ir) added a further seven, which together with Fermanagh now makes a total of 19 of the 40 VCs on the island with records.
The New Atlas hectad map shows that in Ireland and Scotland, L. purpurea is much more scattered, occasional and urban in its distribution than is the case in lowland England and Wales, although Beesley & Wilde (1997) reported it widespread and quite common in urban Belfast, being recorded in 34 1-km squares in the city. Similarly, in their survey of urban inner Dublin, Wyse Jackson et al. (1984) reported L. purpurea locally frequent, mainly S of the River Liffey.
In England, L. purpurea is recorded at the hectad level as being almost omnipresent in the area SE of a line drawn on the hectad map between Bristol and Bridlington and generously scattered in the lowlands northwards to beyond Inverness, chiefly on the eastern side of the island. It is also well represented in Wales, especially in coastal and urban areas of the country (A. Horsfall, in: Preston et al. 2002).
The considerable increase in the species British presence in the 40 years between the two BSBI Atlas surveys probably reflects both a genuine spread of the plant and a better recording effort directed at introduced species, a feature that is now noticeable with most garden plants (Clement & Foster 1994).
Threats
None.