Thank you! I've googled it, and now know why I've seen this in many countries in Europe ( I took the picture in Ireland last week).

Where are you from, cinjodi? English Ivy is firmly established and even a pest in many parts of the world. We don't see the reproductive stage unless it grows up, untrimmed for quite some time, but most of us are extremely familiar with the juvenile stage.

But in the British Isles, including the island of Ireland, it is native and provides one of the big late feasts for insects. Black berries follow for the birds. In its native habitat it is an invaluable wildlife plant.

Interesting trivia: If you take cuttings of the arborescent stage they will keep that form and not revert to the vine form. So you can make yourself an Ivy Tree.

the complete name would be Hedera helix arborescens,

I have noticed the mature form on concrete benches about knee high, flowering at their top (in Germany).

But if the conditions are not sunny enough they do revert and send out creeping vines. I am not exactly sure what factors trigger the flowering stage.

I had to deal with perennial plantings (doing some kind of survey), one had a low hedge (a foot high) of flowering Ivy, but it got shaded so much from taller growing perennials that there appeared several vines that crowded lower perennials eventually.

in at least three plantings I saw it reverting (in partial shade), so IMO it is fancy but nothing if you aim for low maintenance.

'The complete name would be Hedera helix arborescens'. That is slightly misleading. All Hedera helix has the capacity to go into the arborescent state but it does not become a sub species or cultivar when it does so. The name Hedera helix 'Arborescens' is applied only to cutting grown plants from the arborescent stage, not for the flowering tops of any ivy plant. My observation has always been that Ivy will flower when it reaches the top of its support, however low that may be.

I used to grow a shrub form of English ivy in my old garden, Hedera helix 'Erecta'. Rather unique to the species as it grew distinctly upright - no vining at all - and never flowered so never set fruit. Quite the oddity (and a safe one as well) in an area that is known for being overrun with English ivy in its other, more common form. Kind of a handy plant as it was very shade tolerant, didn't mind being dry, was evergreen and never grew much beyond about 3'!

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Yes, 'Arborescens' is a cultivar name implying it is based on a particular instance of a shrub being grown from cuttings of the adult condition of the typical plant. Of course, in practice various people may have rooted multiple different clones over the years and used the same name for these independent introductions.

Giving even a forma name to ivy plants merely having reached sexual maturity seems technically incorrect as such naming is supposed to recognize genetic conditions (same as cultivar and species names) of sets of related plants rather than identify physical states of individual specimens.

Although Hedera helix is also present here as a wild plant the conspicuous, dominating weed ivy infesting communities in the Pacific Northwest is actually Irish ivy (H. hibernica). This tends to produce larger leaves and the hairs on these leaves are different.