Lysimachia punctata L., Dotted Loosestrife
Account Summary
Introduced, neophyte, an uncommon garden escape, probably mis-named.
13 September 1974; Hackney, P.; E shore of Lower Lough Erne.
July to September.
Growth form and preferred habitats
This popular, tall evergreen garden perennial, introduced from SE Europe and SW Asia, is very vigorous and can form clumps up to 120 cm tall. Given its invasive vigour in the garden setting, the famous horticulturalist G.S. Thomas (2004) recommends it only for broad sweeps of self-maintained colour in the wilder parts of larger gardens. On account of its thriving growth, the plant quickly outgrows its allotted space and almost always originates in the wild from discarded material. It then persists and may spread to a limited extent in suitable growing conditions through the possession of a short, thick rhizome.
L. punctata is readily distinguished from L. vulgaris (Yellow Loosestrife) by the flowers being confined to the upper leaf axils and by its entirely green sepals. In comparison, the inflorescence of L. vulgaris is a terminal panicle and its sepals have much darker margins. However, it is important to note that vigorous stems of L. punctata can produce lateral inflorescences similar to the main one (McAllister 1999).
L. punctata is sterile or strongly self-incompatible and it only very rarely sets seed (McAllister 1999). Part of the reason for the lack of seed may be the close, but not usually obligate, relationship of the flower with Macopis solitary bees as pollinator (Simpson et al. 1983).
Fermanagh occurrence

In Fermanagh, L. punctata usually occurs in disturbed wayside situations not far from houses, colonising rough grassland and hedge margins. The earliest record of L. punctata in NI appears to be that of Paul Hackney in Fermanagh in 1974, yet there are now 16 records in the Fermanagh Flora Database from 13 tetrads, very thinly scattered throughout the lowlands on roadsides and in rough or disturbed ground. This suggests that either L. punctata is spreading, or was ignored or overlooked by earlier field workers, as often was the case with naturalised garden introductions.
An interesting observation, which probably contributes to the untended survival of the plant in the wild, is that L. punctata appears to require less soil moisture than other Lysimachia species (Ingram 1960). As a result it is not confined to damp ditches, marshy ground, or fen carr but, in addition, is found on roadsides, waste places and old quarries, all places where people habitually dump garden waste (Reynolds 2002).
On the other hand, the calculated Change Index comparison of the two BSBI Atlas surveys across B & I gives L. punctata the extremely high score of +4.62. This indicates a massive increase in records of the species during the 40 years between the two BSBI Atlas recording efforts. The question remains: is the plant rapidly increasing, or is it simply being recorded now when previously it was ignored? L. punctata has been in garden use since 1658 and was first recorded in the wild in 1853 in Angus (VC 90) (A.J. Richards, in: Preston et al. 2002). Obviously L. punctata has been around for a long time and it is possible that we might be witnessing a real change in its colonising ability.
British and Irish occurrence
Despite the lack of seed, L. punctata appears to have become more frequent in recent decades throughout these islands (Clement & Foster 1994; NI Vascular Plant Database). The New Atlas map shows Dotted Loosestrife is quite frequent and widespread throughout lowland Britain, including on the remote islands of Orkney, Shetland and the Outer Hebrides. In Ireland, it is rather better represented in the north: otherwise, it is very thinly scattered southwards in the western half of the island, with one outlier near Wexford town. However, there are grounds for believing that some records made in recent years may be identification errors, due to another rather similar species, L. verticillaris Spreng., having been introduced to cultivation.
European occurrence and a possible error in B & I recording
The natural distribution of L. punctata is confined to Europe and W Turkey. A morphologically very similar plant with a more easterly, non-overlapping wild range is L. verticillaris Spreng. (Leblebici 1978). The latter is self-compatible and freely sets seed. In the view of the current author (RSF), it appears likely that a single, or a very few clones, of self-incompatible L. punctata have been introduced into garden cultivation and have propagated vegetatively. More recently (perhaps since 1962), however, material of L. verticillaris must have also been introduced to horticulture, traded, distributed and grown by gardeners as 'L. punctata' (McAllister 1999). Thus the current author shares Hugh McAllister's belief that the self-seeding L. verticillaris is producing the rapid increase in records erroneously being referred to as L. punctata around these islands.
L. verticillaris differs from L. punctata in at least five characters, the most easily observed being the petals, which are flushed with orange near their base, and nodes and leaf bases, which are purplish, rather than green (McAllister 1999).
The self-seeding Dotted Loosestrife (L. verticillaris) was introduced to N America as a garden plant and has likewise become a naturalised weed of disturbed ground on roadsides and in fields in the eastern states (Ingram 1960). We are probably safe in assuming the same situation applies on both continents, N America and Europe.
Threats
None.