Eastern hemlock and Hemlock

Eastern hemlock noun - Common forest tree of the eastern United States and Canada; used especially for pulpwood.

Hemlock and eastern hemlock are semantically related. In some cases you can use "Hemlock" instead a noun phrase "Eastern hemlock".

Hemlock noun - Large branching biennial herb native to Eurasia and Africa and adventive in North America having large fernlike leaves and white flowers; usually found in damp habitats; all parts extremely poisonous.

Eastern hemlock and hemlock are semantically related. Sometimes you can replace phrase "Eastern hemlock" with "Hemlock", this terms are similar.