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Myosotis discolor Pers., Changing Forget-me-not

Account Summary

Native, frequent. European temperate, but favoured by agriculture and widely introduced, including in S Africa, India, N America and New Zealand.

1881; Stewart, S.A.; Co Fermanagh.

April to October.

Growth form, variation and preferred habitats

This small, hairy annual has two ecotypes or subspecies that occur in entirely different habitats, one dry and the other wet. The more common form (subsp. discolor) is rather similar in form and ecology to M. arvensis (Field Forget-me-not), behaving as a typical winter annual and is found in a wide range of open, disturbed and bare ground where the soil is dry, warm, sandy or stony. It behaves as a small, weedy, short-lived, spring ephemeral, up to 30 cm tall, flowering and fruiting early in the growing season to avoid summer drought. The established strategy of M. discolour is categorised as SR, ie intermediate between a Stress-tolerator and a Ruderal species (Grime et al. 1988, 2007).

In the past, like Field Forget-me-not, M. discolor subsp. discolor was a cornfield weed, but modern farming technology has put a stop to this behaviour. Subsp. discolor can be recognised by at least the uppermost pair of stem-leaves being opposite rather than alternate and the corolla is up to 4 mm, yellow at first before turning pink or blue. In subsp. dubia (Arrond.) Blaise, on the other hand, none of the stem-leaves are opposite and the corolla is smaller (not more than 2 mm) and is whitish or cream at first (Sell & Murrell 2009).

Subsp. dubia occupies bare patches in wetter, cooler meadow soils, rushy pastures and base-rich flushes, where it grows much taller (up to 30 cm or more) and perhaps behaves as a spring or summer annual (Flora of Connemara and the Burren; Grime et al. 1988, 2007; An Irish Flora 1996; D. Welch, in: Preston et al. 2002; Chater 2010).

Species recognition

The distinctive features of M. discolor are the very small flowers (2-4 mm across), which are yellow to cream in bud, turning from pink to blue as they open and age, thus meriting its Latin scientific epithet and English common name. The fact that the corolla tube is longer than the calyx helps distinguish M. discolor from M. ramosissima (Early Forget-me-not), where the corolla tube is shorter than the calyx and it never has yellow flowers (Garrard & Streeter 1983; New Flora of the BI 1991; An Irish Flora 1996).

Flowering reproduction

M. discolor flowers from May to September, the inflorescence being a lax, terminal, bract-less scorpioid cyme, not much longer than the leafy part of the stem. The flowers are bisexual and the fruiting pedicels are shorter than the calyx. The calyx is bell-shaped, up to 4.5 mm long. The flowers are pollinated by bees and flies and can also self-pollinate (Fitter 1987). As in M. arvensis, the calyx of M. discolor is covered with hooked hairs and does not open or release the four (or fewer) nutlets at maturity, but rather it detaches as a burr-like unit to be dispersed by attaching to passing animals including man (Salisbury 1964). The seed bank survey of NW Europe does not include any mention of M. discolor, but since it has a very similar ecology to M. arvensis which does display prolonged buried seed survival (five years or more), there is some possibility it might be similar for this species (Thompson et al. 1997).

Fermanagh occurrence

In Fermanagh, M. discolor is frequent and widespread and has been recorded in 107 tetrads (20.3% of the VC total), 103 of them with post-1975 records. It is most frequently found in disturbed or otherwise open, warm, sunny, dry, sandy or stony soils in a very wide variety of habitats, but it is also quite frequently found in damp to wet lakeshore and riverbank meadows and pastures and along damp roadside verges and woodland tracks. As the tetrad distribution map shows, it is more frequently recorded to the south of Lough Erne, perhaps a response to the greater prevalence here of dry, base- and nutrient-medium to rich soils on which it performs well, although it is very clearly not confined to these.

Irish occurrence

In Ireland, M. discolor is very widespread across the whole island but, curiously, is more frequently and more consistently recorded in NI than is the case in the RoI. The species is more widely scattered in the RoI, with a more easterly occurrence of records, which might possibly reflect more acidic soils in the west of the country, or perhaps merely result from an absence or scarcity of resident plant recorders in springtime when the plant is most conspicuous (An Irish Flora 1996; New Atlas).

British occurrence

M. discolor is well distributed across Britain from the Channel Isles to Orkney (VC 111) and Shetland (VC 112) in the north. It is generally lowland, but does reach an altitude of 845 m in Westmorland (VC 69). In common with the situation in Ireland, M. discolor is rather scarce and local in parts of N England and Wales (Garrard & Streeter 1983). The BSBI New Atlas dataset indicates a widespread decline in populations has occurred in S & E England since around 1950, undoubtedly associated with better management of weeds in agricultural fields since that time (D. Welch, in: Preston et al. 2002).

European and world occurrence

M. discolor belongs to the European temperate phytogeographic element although it shows a definite sub-oceanic tendency in its distribution. It is present in most of Europe from Iceland southwards and east to Latvia and C Yugoslavia. It is also found in N Africa, on the Azores and on Madeira, in the latter of which the population is distinguished as subsp. canariensis (Pitard) Grau. Subsp. discolor occurs throughout the range of the species, but subsp. dubia is confined to W Europe (Sell & Murrell 2009). Since the species is often associated with agriculture, it has been introduced for instance into S Africa, India, N America and New Zealand (Hultén & Fries 1986, Map 1554).

Threats

None.