Lysimachia vulgaris L., Yellow Loosestrife
Account Summary
Native, common but rather local. Eurasian temperate, but widely naturalised.
1884; Barrington, R.M.; Lough Erne.
April to October.
Growth form and preferred habitats
Up to 150 cm tall, a rhizomatous and clump-forming perennial with opposite or 3- or 4-whorled 9 × 3.5 cm, downy-coated leaves, L. vulgaris is a vigorous, panicle-forming, yellow-flowered plant of ditches, damp to wet meadows, sheltered tall herb marshes, swampy woods and lakeshore fen-carr. L. vulgaris is easily distinguished from the only other tall, yellow-flowered member of the genus in Fermanagh, the much rarer garden escape L. punctata (Dotted Loosestrife), by that species more branched inflorescence, calyx teeth without a darker, orange margin and leaves with at most a few scattered hairs on their margins (Webb et al. 1996).
Fermanagh occurrence
Yellow Loosestrife is a conspicuous and characteristic perennial of wet ground around the shores of Upper Lough Erne. It also occurs in similar damp to wet situations scattered throughout the county, reaching a total of 114 tetrads, 21.6% of those in the VC. However, while it is frequent and locally abundant around the margins of the larger lakes in sheltered, well-grown, tall herb or wet woodland conditions, it is very much more scarce or totally absent around many of the smaller lakes in the county. Further evidence of the local occurrence of Yellow Loosestrife is given by the fact that of the over 500 records in the Fermanagh Flora Database, very few derive from river margins. The species has only been found on three – the Woodford, Finn and Swanlinbar rivers.
The fact that a vastly greater number of man hours have been spent on lake surveys in Fermanagh compared with those RHN and the current author (RSF) have spent walking the riverbanks, must unquestionably be part of the reason for this apparent discrepancy. However, another factor must be the strenuous efforts the NI Water Service and local farmers continually make to keep drainage channels open, removing tall herb communities that threaten to clog waterways and canalising ditches and streams. Harron (1986) noted very much the same restricted pattern of occurrence of this species around Lough Neagh and its associated larger water bodies. He attributed this to drainage and reclamation works limiting the plant to isolated patches amid remnants of scrub and reed beds (Flora of Lough Neagh).
Irish occurrence
L. vulgaris is widespread in central and northern parts of Ireland lying northwest of the River Shannon, but it is much scarcer or absent from both the better farming country in the SW of the island and from the more acid, peat bog conditions of the far south and the western seaboard (Preston et al. 2002).
British occurrence
L. vulgaris is widespread throughout England and Wales, but it is much rarer in Scotland and really is only frequent there in the central lowlands, although it does reach Aberdeen on the north-east coast. As it is essentially a lowland species, the high Scottish mountain ranges clearly have provided an impassable geographical barrier preventing spread further north and north-west.
The calculated Change Index between the two BSBI Atlas dates (1962, 2002) has a value of +0.22, yet despite this overall apparent increase in distribution, which could well be due to differences in recording effort, analysis of the New Atlas survey data indicates that most of the observed habitat losses due to drainage and clearance of watercourses, took place after 1950 (A.J. Richards, in: Preston et al. 2002).
Variation
L. vulgaris is a phenotypically very variable species, ie able to adapt and modify its growth form and characteristics depending on the particular ecological conditions under which it lives. Generally the plant grows in small groups, rooting in organic mud, but in some wet situations, including when standing in permanently flooded ground, it can develop long, above-ground, horizontally spreading stolons.
Flowering reproduction
The size, colour and, very unusually, even the shape of the flower organs can change to some extent in relation to the level of light. Except when in deep shade, the plant bears a large number of conspicuous yellow flowers in July and August on long, branched, leafy panicles. They contain no nectar but have plenty of pollen in their large anthers, which generally proves attractive to hoverflies, solitary bees (particularly Macropis species) and certain wasps, although the flowers can also self-pollinate and fertilise if they remain unvisited (Proctor & Yeo 1973; Simpson et al. 1983).
The fruit capsule contains only three or four discoid seed and these can float for between one and four weeks, allowing the plant to disperse within the lake, river and stream water system. Seed has been identified in the crop of Woodpigeon, although this does not necessarily mean that the birds disperse it (Ridley 1930, pp. 220, 498). Yet apart from seed transport in mud, how otherwise could the species cross dry land and colonise additional, isolated waterbodies?
Horticultural use
A garden form of the species exists with slightly larger flowers with petals red at their base, var. grandiflora. Allen (1968) noted this form 'jumping over the garden wall' and actively spreading in semi-wild boggy terrain on the Isle of Man. The species is sometimes included in wild-flower seed mixtures, widely sown in disturbed ground throughout these islands in recent years (Sell & Murrell 2014).
European and world occurrence
Occasional in garden cultivation, L. vulgaris is widespread throughout most of Eurasia except the extreme north. It was introduced and became naturalised and developed into a serious invasive weed in eastern N America and to a lesser extent in New Zealand (Hultén & Fries 1986, Map 1477; Webb et al. 1988).
Names
Grigson (1987) provides two origins of the genus name; the Greek 'lusimachion' translates as 'loosestrife', which means 'ending strife', but Pliny believed the name commerated Lysimachos, a King of Thrace.
Threats
None.