Answer:

ELM

Answer	Crossword Clue
ELM	"Nightmare" street
ELM	Deciduous tree
ELM	Massachusetts state tree

ELM	Nightmare street
ELM	Nightmarish street
ELM	Slippery ..
ELM	Slippery tree?
ELM	"A Nightmare On .. Street"
ELM	Dutch ... disease
ELM	Freddy's street
ELM	MEL in a tree?

ELM	Shady tree
ELM	Wych ..
ELM	Endangered tree
ELM	Popular street name
ELM	Shade tree
ELM	Boston's Liberty Tree, e.g.
ELM	Slippery ...
ELM	Stately tree

ELM	Tree afflicted by phloem necrosis
ELM	Barrel material
ELM	Street name
ELM	Tree
ELM	Shade source
ELM	Sun blocker
ELM	Graceful brancher
ELM	Shade provider

ELM	Bay State's official tree
ELM	Massachusetts's state tree
ELM	Shade supplier
ELM	Hardwood provider
ELM	Shipbuilding wood
ELM	Street tree
ELM	Nightmare street?
ELM	Slippery tree

ELM	Wood used to make hockey sticks
ELM	America's Liberty Tree was one
ELM	Tree dubbed the "weed of Worcester"
ELM	Plant dubbed "the Weed of Worcester"
ELM	Colonnade tree