Here is a set of CAD plant symbols of tree symbols in elevation view to download. Each is presented as a separate CAD drawing as blocks inside a single drawing. The tree symbols in elevation are available in both metric and Imperial (USA) versions.

Why develop palettes?
Rather than add more and more symbols (blocks) to the gCADPlus setup file, thereby making it large and unwieldy, we have developed a series of palettes that allow extra symbols to be added to gCADPlus. Each link takes you to a page that allows you to download a single gCADPlus file. Once downloaded, use the BLOCKS command (or File > Insert) and then browse the option to locate and insert the new file while working on your current design.
Tip: When using the palette, it is a good idea to explode the incoming drawing to see the new symbols immediately. Drag into position and scale if required.
Click here to download a copy of this palette suited for use in the metric environment.
Click here to download a copy of this palette of trees suited for use in the imperial (USA) environment.
This small movie shows how to download a palette of extra symbols to gCADPlus and use them in a developing design.