Ivy in Britain

[Mihcis]

I heard there are two species of ivy in Britain: Hedera helix and Hedera hibernica.

Is there a way for an amateur to tell them apart?

[Hedera]

Difficult; Hedera helix has white hairs on the underside of leaves, hibernica yellowish hairs.

[Dorts]

Just to add to Hedera's info; H. ssp. hibernica does tend not have 'marbled' markings on the leaves which are generally larger.
It is said that the only Ivy in Cornwall is Hedera ssp. hibernica, but having lived there for several years I'm not so sure.
Dorts.

[AlanS]

Hedera helix and Hedera hibernica, formerly considered subspecies, are recognised as separate species in Stace ed. 3. Biologically this is seemingly correct as they have different chromosome numbers and, so far as I am aware, they are not known to hybridise. On the other hand, they are not always easily separated on macro-morphological characters and I have always felt that subspecific treatment was better.

Anyhow, I cannot say that I have found the supposed hair colour much use, but the shape of the leaf hairs provides rapid separation (illustrated in Stace, ed. 3, page 799). Take a fairly young leaf that has not lost its hairs, examine them (with a lens) on the back, towards and around the base of the main vein, and in H. hibernica, the star-like hairs have all their branches more or less flattened against the leaf surface. (Ignore the occasional damaged hair and don't mis-handle the leaves before examination.) In Hedera helix, the majority of the branches of each hair stand away from the surface.

In my own vice-county, Wigtownshire (SW Scotland), I have H. hibernica all round the coast, extending inland in older woods, whereas H. helix often looks to be an introduction. However, H. helix is also undoubtedly native among rocks on moorland and perhaps in some of the inland hedges. I have been recording them separately for many years, and usually can tell them at a glance, even though I always check the hair character just in case.

I think Dorts is right to be suspicious of the overly neat suggestion that all Cornish Hedera is hibernica. I cannot remember where, but I am sure I have seen H. helix in Cornwall, though looking like a possible introduction, and I would expect it as a native on, say, Bodmin Moor at least.

Alan

[Deb London]

What an interesting thread. I've taken notes.

[Dorts]

Great stuff as usual Alan, thanks very much for those most useful ID 'tools'.

Yes, I always thought that the rather sweeping statement in The Flora of Cornwal, that the only species native to the county is H. hibernica to be a little bold. I am sure most of the H. helix I have found there has been introduced with garden material, but not all. Some H. helix found has certainly been contemporary with some very old trees and far from habitation.
Dorts.