The plants in York's pictures often resist classification. His trees say "tree" but are otherwise botanically moot. With their broad leaves and spindly perpendicular trunks, are they young maples? sycamores? or a composite?
...York's trees are in fact his most overtly realized characters. They're more philosophically disposed than his people, who, although allegorical in their own right, tend to appear introspective or stunned, caught up in consequences left undeclared.
Where the people fade in and out even as they show themselves, the trees, advancing always in full leaf, project a quasi-permanence as custodians—floating modifiers of the presiding topography of earth and sky. Like the people, they coexist but never touch. The skies beat laterally against them, enlargingupon stacked tiers of horizon.
(http://www.davisandlangdale.com/BerksonIdyllsofAlbertYork.pdf)