Geometrees are exactly that…plants that are largely constructed from geometry and do not depend upon image transparency for foliage effects. This ensures that they are effectively render-ready in a variety of packages, such as V-Ray, Podium etc.
Because of this, they do have a rather high face count (though nothing like as high as XFrog or Onyx)…so use sparingly in SketchUp.
Hint: The trees are supplied with the leaf texture at full opacity. When rendering, you may like to try turning the opacity down to somewhere in the range 85-99. It mutes the colour and helps disguise the simple kite shape used to keep the poly count down.