True Firs East of the Cascade Mountains: The Genus Abies
Subalpine Larch: Larix lyallii - Oregon evidently lumps Larix lyallii into Larix occidentalis (See below.)
Alpine Larch, Hackmatack, Lyall's Larch, Montana Larch, Mountain Larch, Subalpine Larch, Tamarack, Western Larch: Larix occidentalis (Synonym: Larix lyallii)
Engelmann Spruce: Picea engelmannii (Synonyms: Picea engelmannii var. engelmannii, Picea engelmannii ssp. engelmannii, Picea engelmannii var. glabra, Picea glauca ssp. engelmannii, Picea glauca var. engelmannii)
Pines East of the Cascade Mountains: The Genus Pinus
Douglas Firs East of the Cascade Mountains: The Genus Pseudotsuga
Hemlocks East of the Cascade Mountains: The Genus Tsuga