"the branches appear flattened as if they had been ironed" (Rocky Mt Tree Finder)
These are western red cedars, Thuja plicata. Scientific (Latin) names may seem pretentious but in this case they clearly are useful, for there are many kinds of “cedars” in the world. They aren’t just different species either, but completely different genera (plural for genus). In other words they aren’t even closely related. Here are some examples:
True cedars belong to the genus Cedrus. They’re native to the western Himalayas and the Mediterranean region. Examples include Deodar cedar and the Cedars of Lebanon.
The red cedar we talk about in South Dakota actually is a juniper, Juniperus virginiana. The wood made great fenceposts before steel ones arrived.
The white cedar of Australia, Melia azedarach, isn’t even a conifer. It’s a member of the mahogany family.
|Range of western red cedar, Thuja plicata. Source.|
|It took us forever to tour the Enchanted Red Cedar Forest as there was much to see and ponder.|
|Bases of mature trees often are gracefully buttressed.|
|Branch ends are distinctly flattened and fern-like, making western red cedars easy to recognize.|
|Closeup showing scale-like leaves.|
For more about western red cedars, see the USDA Fire Effects Information System.