Editing Mentha pulegium (section)

==Habitat and ecology==
[[File:Mentha_pulegium_at_Weston_Favell.jpg|thumb|Typical habitat of pennyroyal in a seasonally inundated field by the River Nene in Northamptonshire, UK]]
The habitat of pennyroyal is seasonally damp pasture, where standing water over the winter leaves bare ground in the summer, and where livestock preferentially graze other plants. An analogue of this habitat is found on roadsides, where trampling or disturbance of the ground produces similarly bare soil, particularly where there is waterlogging in winter. It is also found along watercourses, in wet woodland and in abandoned fields.<ref name="CABI" />

In California, where it is considered an invasive species, it occupies a similar niche, in seeps, streamsides, vernal pools and swales, marshes, and ditches. There is some speculation that it may displace native species in these areas.<ref>{{cite web |author=California Invasive Plant Council |title=Mentha pulegium |url=https://www.cal-ipc.org/plants/profile/mentha-pulegium-profile/ |date=20 March 2017 |access-date=17 February 2022}}</ref>

Few animals eat pennyroyal. In Britain, the only insect known to feed on it is the bug ''[[Heterogaster artemisiae]]'' Schilling, which is a seed bug that normally feeds on [[Thymus praecox|wild thyme]].<ref>{{cite web |author=Biological Records Centre |title=Database of Insects and their Food Plants |url=https://www.brc.ac.uk/dbif/}}</ref>

It is considered an [[axiophyte]] in many British counties, because low-intensity pasture is a rare habitat, although it has been spreading in recent decades.<ref>{{cite web |last=Lockton |first=Alex |title=BSBI species accounts: Mentha pulegium |url=http://sppaccounts.bsbi.org/content/mentha-pulegium-0.html#:~:text=At%20the%20species%20level%2C%20Mentha,%2D%20an%20upright%20form%20(var. |access-date=31 August 2010}}</ref> Its [[Indicator value|Ellenberg values]] in Britain are L = 8, F = 7, R = 5, N = 7, and S = 0.<ref>{{cite book |last1=Hill |first1=M.O. |last2=Mountford |first2=J.O. |last3=Roy |first3=D.B. |last4=Bunce |first4=R.G.H. |title=Ellenberg's indicator values for British plants. ECOFACT Volume 2. Technical Annex |url=http://nora.nerc.ac.uk/6411/1/ECOFACT2a.pdf |archive-url=https://web.archive.org/web/20091111045128/http://nora.nerc.ac.uk/6411/1/ECOFACT2a.pdf |archive-date=2009-11-11 |url-status=live |publisher=Institute of Terrestrial Ecology |date=1999 |access-date=29 May 2017 |isbn=1870393481}}</ref>