Hmm, well there is actually a lot of Rhus trilobata (Skunkbush) around here, but they all have the typical, rounded leaves without any pointy tips. Not to mention, their leaflets are all maybe only around ~3/4" long or so... And I definitely also considered Poison Ivy, and have found a similar specimen about 10 miles from here:But the leaves in question here just seem a little too thick and the woody branching form too atypical to be Poison Ivy? As far as Acer negundo (Boxelder Maple), that seems plausible...although this short, bushy form would also be very atypical. And these leaves also look too thick for this, as well. Well, here's a zoomable pic of the original to see more detail...if that helps?

Absolutely a Celtis sp., and likely Celtis occidentalis - Common Hackberry. Sugarberry (Sugar Hackberry) - Celtis laevigata - has a far more southerly distribution and isn't likely to be found wild in New York state. Simple, alternate, likely rough to the touch, look for oblique leaf bases similar to Elm. Later in the season, expect to find the protuberances on the leaves indicative of the Hackberry Nipple-Gall Maker - always a great ID feature. Not being able to see 100% of the plant, the horizontal habit in the picture doesn't indicate anything. I can find low horizontal branching like this from suckers off the shallow roots of established specimens here in the woodlands at the Valley.

I had to look it up, but exactly what floral said about the opposite foliage. I posted it on a German site with little hope, uploading pics is cumbersome overthere, but added to write, sorry, so floral, there seem to be similar information structres (or likemindedness?) as I was shown the same link from the German forum like the one you posted... ;-) there are some fellow nerds, and one was online today and suggested a Forsythia species (or hybrid thereof), Forsythia suspensa or similar Pics of foliage at Daves garden so far this is the best fit IMO. The twig and bark had my brain come up with "Forsythia", and that might be the reason why, it grew at a tram station from some joints between stone slabs/ paving, so my guess was seedling. Dont know whether hybrids would set seeds, but with species it would be more likely, wouldnt it?

I just received eleutherococcus, the variegated form, this spring from Bamboo Plants and it has done well so far Funny you mention this @chouchou_gw as the spot in question just had an eleutherococcus, the variegated form! https://www.gardenweb.com/discussions/1671848/eleutherococcus-acanthopanax-sieboldianus-variegatus I searched it out specifically to go in the corner of the then newly created garden bed.....over 12 years ago I bet as its claim to fame was its ability to thrive in dry shady conditions. It did well for many years but slowly and surely it lost is variegation and its vigour and so I dug out what remained of it. (I got this specimen at a brick and mortar nursery but almost for sure not would I be able to find it similarly and doing a search I was surprised to see it at BAMBOO.) The single kerria, Golden Guinea is much nicer than the usual double flowered variety. "rosa/camp", I did have the GG many years ago and I ditched it as the foliage inevitably developed some sort of "blight", often leading to defoliation. But *if* I was to try it again I would go with the single. @gardengal48 (PNW Z8/9)..great list. I will look carefully at each one. (If a mac hydrangea were to go there it would have to be in a container, of which I have several, as otherwise, very likely there would be no blooms, if planted in ground. And in fact that is what I might do i.e. place the containerized mac in that spot come May. ('gg' your suggestion of Clethra (alnifolia) is interesting...I like this plant but it probably needs more moisture than this location can provide.) @mad_gallica (z5 Eastern NY), I have always admired "Bottlebrush Buckeye" but have been put off by its potential size (although if as you say it grows slowly then maybe it is a moot point).