Lysimachia punctata L. (incl. hybrids with L. verticillata (Greene) Hand.-Mazz.) (SE Eur., SW As.) – A frequently naturalized and increasing escape from cultivation, known at least since the first half of the 19th century and probably even earlier (this species was originally described by Linnaeus based on Dutch plant material: “Habitat in Hollandia inter arundines”).
It is fairly equally dispersed in Belgium. Up-to-date information on its distribution in Belgium is available here: http://waarnemingen.be/soort/view/7023.
Lysimachia punctata is often found in natural or semi-natural habitats (e.g. in damp woodland and -meadows), often even in remote locations (Parent 1998), despite its sterility. It is not (yet) considered an invasive species in Belgium.
The exact identity of the plants found in cultivation in western Europe is somewhat unclear. McAllister (1999) argued that – at least in part – British plants in fact belong to a related species, L. verticillata (Green) Hand.-Mazz. (as L. verticillaris Spreng.), a native from West Asia (Caucasia, Crimea, Iran and Turkey). Moreover, this species is thought to be the usual garden plant, L. punctata being much rarer. It is true that Belgian plants of the latter are rather variable and two extremes are discernable: on the one hand plants with a lax inflorescence with flowers on pedicels up to 25 mm long and with distinctly petiolate leaves (petiole up to 20 mm long); on the other hand plants with a dense inflorescence of (sub-) sessile flowers and nearly sessile leaves. These plants roughly correspond with Lysimachia verticillata and L. punctata respectively. McAllister (1999) add some extra distinguishing features but some (e.g. corolla with or without orange throat) seem to be unreliable. L. verticillata also is, contrary to L. punctata, fully fertile. The taxonomic value of this split, however, long remained, especially since populations that are more or less intermediate in morphology seem to occur. In Turkey, where both are allopatrically distributed, plants with intermediate features have also been recorded, although only exceptionally (Leblebici 1978). Stace (2010) therefore preferred to merge both in one variable L. punctata. Sell & Murrell (2014), on the contrary, still accept both as distinct species. Triponez & al. (2016) demonstrated that both are distinct species and highlight the absence of natural hybrids between the two in their native area. Naturalized populations from northern Europe, however, were shown to be hybrids, likely produced through horticultural practices.
For convenience and for what it is worth, both these species are opposed in the following couplet:
1 Leaves nearly sessile, the longest petioles up to 2 mm long. Inflorescence dense, flowers relatively few, (sub-) sessile === L. punctata
Leaves with distinct petiole, 5-20 mm long. Inflorescence lax, flowers rather numerous on pedicels up to 25 mm long === L. verticillaris
The application of the name Lysimachia verticillaris in the British Isles probably is erroneous. In his original description Sprengel referred to the leaves that are opposite and obtuse-rounded at apex, a character not encountered in western European plants of alleged L. verticillaris (see here for the original species description http://www.biodiversitylibrary.org/item/29479#page/42/mode/1up and here for an image of the lectotype: http://www.mobot.org/MOBOT/Research/LEguide/specimen-images/120/1971.html).
Molecular data have shown Lysimachia punctata and L. vulgaris to be only remotely related. Yet, some forms of L. punctata (especially those referable to L. verticillaris with long pedicelled flowers in a rather lax inflorescence) may somehow resemble L. vulgaris. L. punctata is said to be glandular hairy while L. vulgaris is eglandular hairy (Tison & de Foucault 2014), with usually long septate hairs. However, some forms of L. vulgaris are glandular hairy; these have been segregated as L. davurica Ledebour, a species widely distributed in Asia but also introduced elsewhere, for instance in Australia (Kodela 2006). It is accepted as a distinct species by most authors (e.g. Shteinberg 1967, Jia 2003) although molecular data suggest a close relationship (Hao & al. 2004). According to Klatt (1866) the presence or absence of glands is a constant character and of taxonomic value. Pax & Knuth (1905) further add that leaves are opposite in L. davurica (vs. ternate) and lanceolate to linear. This species should be looked for in Belgium.
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Selected literature:
Clement E.J. (1982) Confusion between Lysimachia ciliata and L. punctata. B.S.B.I. News 31: 23. [available online at: http://archive.bsbi.org.uk/BSBINews31.pdf]
Hao G., Yuan Y.M., Hu C.M., Ge X.J. & Zhao N.X. (2004) Molecular phylogeny of Lysimachia (Myrsinaceae) based on chloroplast trnL-F and nuclear ribosomal ITS sequences. Mol. Phylogenet. Evol. 31(1): 323-339.
Jia X. (2003) Lysimachia L. In: Wu Z.Y. & Raven P.H. (eds.), Flora of China, vol. 15: 39-189. Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis. Available online at: http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=119206]
Klatt F.W. (1866) Die Gattung Lysimachia. Kessinger Publishing, LLC: 98 p.
Kodela P.G. (2006) Lysimachia (Myrsinaceae) in New South Wales. Telopea 11(2): 147-154. [available online at: https://www.rbgsyd.nsw.gov.au/science/Scientific_publications/telopea/view_contents/b-view_contents?sq_content_src=%2BdXJsPWh0dHAlM0ElMkYlMkZwbGFudG5ldC5yYmdzeWQubnN3Lmdvdi5hdSUyRlRlbG9wZWElMkZyZXN1bHRzLnBocCUzRldoZXJlJTNEQXJ0UGFyZW50UmVmJTNEJTI1MjczJTI1MjclMkJhbmQlMkJBcnRWb2x1bWUlM0QlMjUyNzExJTI1MjclMkJhbmQlMkJBcnRJc3N1ZSUzRCUyNTI3MiUyNTI3JmFsbD0x]
Leblebici E. (1978) Lysimachia. In: Davis P.H. (ed.), Flora of Turkey and the East Aegean Islands, vol. 6: 135-138. Edinburgh: Edinburgh University Press.
McAllister H.A. (1999) Lysimachia punctata L. and L. verticillaris Sprengel (Primulaceae) naturalised in the British Isles. Watsonia 22: 279-281. [available online at: http://archive.bsbi.org.uk/Wats22p279.pdf]
Parent G.H. (1998) Notes chorologiques et écologiques (1992-1996) sur la flore de la Wallonie et des territoires adjacents. Adoxa 18: 11-24.
Pax F. & Knuth R. (1905) Primulaceae. In: Engler A. (ed.), Das Pflanzenreich 22. [available online at: http://www.biodiversitylibrary.org/item/71654#page/5/mode/1up]
Sell P. & Murrell G. (2014) Flora of Great Britain and Ireland. Vol. 2 Capparaceae – Rosaceae. Cambridge University Press, Cambridge: 616 p.
Shteinberg E.A. (1967) Lysimachia. In: Komarov V.L. (ed.), Flora of the USSR, vol. 18: 83-215. Jerusalem: Israel Program for Scientific Translation.
Stace C. (2010) New flora of the British Isles, 3th ed.: XXXII + 1232 p. Cambridge University Press.
Tison J.-M. & de Foucault B. (coord.) 2014) Flora Gallica. Flore de France. Editions Biotope, Mèze : xx + 1196 p.
Triponez Y., Şepitci B. & Alvarez N. (2016) Genome fingerprinting confirms the species status of the Loosestrifes Lysimachia punctata and L. verticillata (Primulaceae). Plant Ecology and Evolution 149(3): 335-338. [available online at: http://www.ingentaconnect.com/contentone/botbel/plecevo/2016/00000149/00...