I've visited the plant this summer - I'd say E. x pseudovirgata, and probably the same as the 1966 plant. Also mentioned in I Lawrence's Wild Flowers of Cleveland. Same or v similar plant also found on Seal Sand roundabout, near the fire station! Yet another alien gem!

list can be dowloaded from here: plantsbiodiversityecosystems.wordpress.com/wp-content/u...

Back at base, and we looked at the hairs in the throat of the calyx tubes. This was fascinating.
Mentha pullegium (right) compared with M. x gracilis.
Both had hairs within the calyx tube, but M. pullegium had a clear cone-shaped, ring of hairs.

M. suaveolens as an alien can look like that!

Hi Benrl... where did you find this one? Alnwick again? Wow! Another v interesting specimen. It has got a lot of M. suaveolens characteristics, but does not quite fit as you spotted. I'd be very cautious about naming it straight away, before observing more into detail. Specimen and/or location?

Thanks very helpful!

One more thing - I see that there are no recent records of M. x smithiana in the Alnwick area - would you send me the location? or submit your record to the BSBI (with due reservation about the identification)? Thanks!

My pleasure, don't hesitate to send me pictures of mints!
The key in Stace mostly gets you to the right direction but it can be hard to use!
Good luck