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Mimulus guttatus DC., Monkeyflower

Account Summary

Introduction, established neophyte of garden origin, occasional to locally frequent.

1892; Praeger, R.Ll.; Inish Dacharne peninsula, Lower Lough Erne.

Throughout the year.

This established western N American alien is a 19th century garden escape, now naturalised in or near streams or other wet, muddy lowland situations throughout most of the British Isles. A vigorous, stoloniferous, patch-forming aquatic, up to 30 cm tall, it both seeds itself abundantly and spreads vegetatively in autumn to form creeping or clumping monocultural patches (Sell & Murrell 2007). The species has very successfully dispersed since it first appeared in the wild in Abergavenny, S Wales in 1824 and now extends in a scattered manner across Britain from the Channel Isles to Shetland (Ellis 1993; A. Horsfall, in: Preston et al. 2002).

It has been recorded in 61 Fermanagh tetrads (11.6% of the total in the VC), 55 of them with post-1975 records. As the tetrad distribution map indicates, Monkeyflower is widespread on muddy stream-sides and lakeshores across the VC, but is most frequently found in the east of the county.

Elsewhere in Ireland, M. guttatus has been recorded in at least 31 of the 40 VCs (Cen Cat Fl Ir 2), including all those in the north of the island. The New Atlas hectad map, however, displays recent records from only 16 Irish VCs. The atlas is very clearly in error since this count does NOT include Fermanagh – where the records actually fall into as many as 19 hectads!

M. guttatus has numerous blood red spots on the bright yellow lower lip of the open, two-lipped flowers, which are solitary in the axils of upper leaves. A number of other closely related and difficult to distinguish American Mimulus species and hybrids of garden origin have also escaped and become naturalised in wet, lowland places.

Fermanagh Occurence

Threats

This alien is very probably still spreading.

Mimulus guttatus × M. luteus (M. × robertsii Silverside), Hybrid Monkeyflower

Introduction, garden escape. Very rare, but probably overlooked and under-recorded.

4 July 1997; McNeill, I.; Tempo River at Tonyglaskan Bridge.

All apparently in July.

This hybrid, rhizomatous or stoloniferous perennial Monkeyflower of garden origin was first recognised in Britain in 1964 and only properly named in 1990. It is an established garden escape that has already been recorded scattered throughout B & I, but with a predominance in NW England, S Scotland and N Ireland (Ellis 1993; Clement & Foster 1994; New Atlas). At the moment, the mapped distribution as displayed in the New Atlas in the opinion of the current author (RSF) reflects only the home territory of the interested recorders of this taxon.

Two recorders have been looking out for this plant in Fermanagh and the seven records in the NE of the county made by Ian and David McNeill are very probably just the beginning of the story for this taxon. RHN and the current author (RSF) are sure it has been overlooked elsewhere, or been mistaken for the undoubtedly much more frequent M. guttatus (Monkeyflower) – a situation very commonly found throughout these islands (A. Horsfall, in: Preston et al. 2002).

Like M. guttatus, which is one of the parent species, the hybrid grows in shaded, wet, muddy or shingly soils by flowing water, or in flushes on marshy or fen-rimmed lakeshores. It reproduces not only vegetatively by fragmentation of the short, brittle stolons, but also by seed, since it has formed a hexaploid amphidiploid form by carrying out spontaneous chromosome doubling (Mimulus peregrinus Vallejo-Marin (New Monkeyflower)), that has restored sexual fertility to the previously sterile triploid hybrid (Sell & Murrell 2007; Stace et al. 2015).

The McNeills have recorded sufficient M. × robertsii in Tyrone (H36) to regard it as being quite common there (McNeill 2010). This hybrid has previously been recorded in Co Antrim (H39) and in at least five other Irish VCs (Cen Cat Fl Ir 2; FNEI 3; Cat Alien Pl Ir). The most accurate picture of Mimulus distribution is presented in the hectad map published in Stace et al. (2015).

The remaining Fermanagh record details are (some dates vague): Killerbran Bridge, Colebrooke River, 1987-99, I. & D. McNeill; stream at Glengesh, 7 km NE of Tempo, 1987-99, I. McNeill; Tempo River at Tonyglaskan Td, 1987-99, I. McNeill; stream at Jamestown House, Magheracross, 2000, I. McNeill; Pollboy Bridge, Colebrooke River, 16 July 2000, I. McNeill; and Derryloman, Colebrooke River, 16 July 2002, I. McNeill.

Threats

Probably spreading along with the M. gutattus parent and perhaps replacing it, especially on higher ground.