There are a variety of wooded landscapes at the Arboretum. The Japanese maple looks like a large Bonsai.

Planting Fields Arboretum, LI, NY 6/29/2019 
Japanese Maple (Acer palmatum), Planting Fields Arboretum, LI, NY 6/29/2019 
Japanese Maple (Acer palmatum), Planting Fields Arboretum, LI, NY 6/29/2019 
Planting Fields Arboretum, LI, NY 6/29/2019 
Planting Fields Arboretum, LI, NY 6/29/2019 
Viburnum, Planting Fields Arboretum, LI, NY 6/29/2019 
Planting Fields Arboretum, LI, NY 6/29/2019

As a kid growing up on Long Island I was aware of Planting Fields but somehow never went there—in contrast to the Theodore Roosevelt home, which I visited several times over the decades. Have you also been to the Theodore Roosevelt site?
I have, and it is a lovely place.
Beautifully big bonsais
Thanks Carl 😀