Green ash (Fraxinus pensylvanica)
Ash is the “A” in MADCAPHORSE (the memory clue for opposite-leaved woody plants). Ash twigs are moderately thick (about like a pencil), with a true terminal bud.
In side view, the leaf scars are remote from one another. (Compare to maple, wherein the leaf scars nearly touch one another).
Ash is one of those genera where winter characteristics are useful year-round. To distinguish the common upland forest tree white ash (Fraxinus americana) from the very similar low(er)-land species green ash (F. pensylvanica), note how the leaf scars of white ash wrap partly up and around the bud, whereas the leaf scar of green ash has a horizontal top edge, with the bud perched above it.
Another twiggily (twiggily?) distinct ash is blue ash, the scientific name of which is very appropriately Fraxinus quadrangulata, meaning “4-angled.” It’s also called “winged ash.”