'Keithsform' is a hybrid of Acer truncatum and Acer platanoides discovered in Oregon. A. truncatum is native to China and Far East Asia. A. platanoides is native to Europe and Western Asia.
Acer 'Keithsform', often called Norwegian Sunset Maple, is a rapidly growing, uniformly branched deciduous tree discovered as a chance seedling in a bed of Shantung maples (Acer truncatum) in Oregon (Learn2Grow.com)