Martin Rand schreef
Aha. The plot thickens.

Stace (New Flora of the British Isles, 2nd edn, 1997) reckons H.
algeriensis Hibberd, which he says is _not_ the same as H. canariensis
Willd., but _is_ the same as some others' H. canariensis, is a distinct
species and can beseparated from H. helix on the colour and form of the
hairs on leaves and young stems, and then from H. colchica on the number of
rays on the hairs. He gives 2n=48 for H. helix ssp. helix, 2n=96 for H.
helix ssp. hibernica, 2n=96 for H. algeriensis, and 2n=192 for H. colchica.

Clement and Foster (Alien Plants of the British Isles, 1994) reckon that
H algeriensis Hibberd and H. canariensis Willd. _are_ for the same plant,
which should be H. helix ssp. canariensis (Willd.) Cout., but as theirs is
simply a catalogue they don't give diagnostics.

I don't have Flora Europaea to hand, unfortunately. (Or perhaps
fortunately - it might give me another story :-)

IPNI gets you first usage, but isn't much good on relating these
nomenclatures, unfortunately.

+ + +
Yes, IPNI just gives first publication. IPNI reports a name by "Hort." for
both Hedera algeriensis and Hedera canariensis: these may or may not be the
same as Hedera algeriensis Hibberd and Hedera canariensis Willd.

Since the RHS Plantfinder accepts both species there must be something in
it.
PvR