Mentha arvensis × M. spicata (M.
× gracilis Sole), Bushy Mint
Account Summary
Introduction, very rare.
1990; NI Lakes Survey; unnamed Lough, Tullyvocady Td.
Fermanagh occurrence
The Fermanagh Flora Database contains a solitary record of this spontaneous hybrid between a native mint (M. arvensis (Corn Mint)) and an alien, introduced mint (M. spicata (Spear Mint)), which was discovered by the NI Lakes Survey in 1990 on the damp shore of a small, unnamed lake. A tall perennial, stems 30-90 cm, with a creeping rhizome, this is an extremely variable plant and therefore a difficult hybrid to identify with certainty. It is most like its M. arvensis parent, differing in its very short, narrow calyx teeth and its high degree of sterility. The herbarium label in BEL indicates that it was identified by its pungent odour when fresh. Plants of this hybrid arising spontaneously in the wild are hairy (pubescent), while those of garden origin are glabrous or almost so and arise in the wild as escapes or garden discards (K. Walker, in: Preston et al. 2002).
While it is sometimes grown in gardens, this hybrid is unfamiliar to many recorders in Ireland at least and, therefore, could very easily be overlooked or mistaken for the more frequently occurring M. × verticillata (Whorled Mint), resulting in it probably being under-recorded.
Irish occurrence
The New Atlas hectad map and that in The Hybrid Flora of the British Isles (Stace et al. 2015) both show that M. × gracilis is only sparsely recorded in Ireland, although O'Mahony (1975, 1995) reports it widespread in Co Cork (H3-H5), particularly along rivers. There have been rare recordings from a total of 18 Irish VCs over the years, many of which are regarded as garden escapes or discards, but apart from Co Cork, very few reports of this plant have appeared in recent years (Cat Alien Pl Ir).
The hectad map in Stace et al. (2015) displays data for Ireland from a total of 43 hectads, five where both parents occur, 23 where the hybrid and M. arvensis overlap, none where the hybrid and M. spicata overlap and 15 squares where the hybrid is independent of both parents.
British occurrence
In Britain, in comparison with Ireland, M. × gracilis is very much more frequent and widespread in lowland areas, although it is rather scarce in the English East Midlands. In Scotland, the hybrid becomes rare and ± coastal northwards (Stace et al. 2015). For comparison with Ireland, the equivalent hectad statistics from the distribution map in The Hybrid Flora of the British Isles are: a total of 645 hectads, 468 where both parents occur, 112 where the hybrid and M. arvensis overlap, 39 where the hybrid and M. spicata overlap and 26 where the hybrid occurs independent of both parents (R.M. Harley, in: Stace et al. 2015).
European occurrence
M. × gracilis is widespread over most of Europe (R.M. Harley, in: Stace et al. 2015).