'Myrtle trees' in the Bible

I saw by night, and behold a man riding upon a red horse, and he stood among the myrtle trees that were in the hollow; and behind him there were red, speckled, and white horses.

And the man that stood among the myrtle trees answered and said, These are they whom the LORD has sent to walk to and fro through the earth.

And they answered the angel of the LORD that stood among the myrtle trees, and said, We have walked to and fro through the earth, and, behold, all the earth sits quietly, and is at rest.