largest in Washington State

Magnolia acuminata, commonly called the cucumber tree
(often spelled as a single word "cucumbertree"),
cucumber magnolia or blue magnolia, is one of the
largest magnolias, and one of the cold-hardiest.
It is a large forest tree of the northeastern United States
and Southern Ontario Canada. It is a tree that tends to occur
singly as scattered specimens, rather than in groves.

from: Wikipedia