Botanising in Huntingdonshire, Yorkshire and Beyond: Atlantic Ivy

Sunday, 18 October 2020

Atlantic Ivy - Overlooked as a Garden Escape?

Atlantic Ivy (Hedera hibernica) is the dominant ivy along the western fringes of Britain, while further east and inland it is generally considered to be replaced by Common Ivy (Hedera helix). The very robust cultivar 'Hibernica' (also known as 'Irish Ivy') being the exception to this, having been widely planted historically and subsequently has spread widely in suburban areas, railway banks and woodland. Despite this it still seems to be under-recorded. In part this is because in some counties it isn't recorded to cultivar level, instead being lumped under Atlantic Ivy. However, there do seem to be some genuine large gaps that are inconsistent with its ubiquity elsewhere. The BSBI database still lists it and maps it under Common Ivy, which also may confuse matters.

Images of Hedera hibernica 'Hibernica', Swillington Park (VC64)

But this is not the only form grown in gardens, and some cultivars are likely to have been grown for as long as 'Hibernica' and therefore are equally likely to have escaped. I was reminded of this recently, when walking through the woodland on the edge of Oulton Park (VC63). My eye was drawn to what at first glance was a carpet of ivy mixed with abundant tree seedlings, but closer inspection showed these 'seedlings' to be part of a very peculiar and heterophyllous ivy. A few young shoots were gathered to look at under the microscope later, and when I did I found the underside of the youngest leaves (the only reliable place to look, and ignoring the leaf margin and major veins) to have a cover of hairs (trichomes) flat to the leaf surface. So, it was a form of Atlantic Ivy, an identification kindly confirmed later by Hugh McAllister, author of the excellent recent monograph on the genus. Hugh also suggested that it looked like the cultivar 'Gavotte', which in itself is interesting as this cultivar is currently considered to be a form of Common Ivy and therefore would need to be reassigned to Atlantic Ivy.

Hedera hibernica cf. 'Gavotte'

This is the third type of Atlantic Ivy I have found in the woodlands around Oulton Park. 'Hibernica' is of course common throughout, but there is another large leaved form which seems to the old cultivar 'Lobatomajor' (and it may sit within a group of cultivars that comprise the Hibernica Group, as the distinguishing distinctively lobed large leaves only start to appear once it starts to climb).

Hedera hibernica 'Lobatomajor'

So inspired by 'Gavotte', and it being a good autumn project now that most plants have gone over for the year, I visited several woodlands in urban fringe locations this weekend to see if I could find more Atlantic Ivy. Something that turned out to be relatively easy, the trick being to focus on those plants with the largest juvenile foliage and/or leaves redolent of 'Hibernica' in shape. None of these plants was as distinctive as the above forms, and instead resemble more typical wild type Atlantic Ivy. But once you get your eye in they do have a distinctive jizz, and the hairs later confirmed these field identifications. It was by no means dominant within the woodlands concerned, but where it has colonised it generally forms dense stands. I'm recording all these finds as neophytes, as I am assuming that they have a garden or other introduced origin. I suspect focussed searching will find them to be relatively frequent in other suburban and urban edge locations.