Library directory: This is the location of the library where all the tree images are saved. Usually this is where you unzipped the downloaded library that comes with Alpha Trees.
Fast loading previews: This will show a button if you do not have PIL (Python Imaging Library) installed. It is used to convert tree previews to a format that can be loaded almost instantly, as opposed to the default blender behaviour that can take minutes to load a lot of previews.
To install the library, just click the button. Be aware that it could take a few minutes.
If you don't want to install the library, Alpha Trees will still work exactly the same, except that the previews will load much more slowly, which can be a problem with large libraries.
Massive thanks to CoreProcess for making this library available.
Auto pack images: When enabled, all tree images that are imported will be packed into the blend file. This prevents the textures being lost if the library is moved.
Show info buttons: Toggles whether info buttons are present around the UI. Turning it off can help to reduce visual noise.
Show Botaniq operator: Only shows if the user has Botaniq installed. If enabled, a "plant Botaniq tree" will be added in the alpha tree creator panel, which can speed up the workflow of converting them.
Botaniq version: Used to know which version of the Botaniq API to use.
Show debug options: Useful for diagnosing problems with the addon, for example if you encounter an error.
Use material previews as tree icons: This uses the rendered preview of the tree material as its icon. It's good as it updates with the material (for example, if you change the colour), however, it can result in squashing of textures.
Increase transparency bounces when adding particles: In cycles, when transparency bounces are set too low, it can result in ugly black boxes where there are too many layers of transparency on top of each other. When enabled, this will automatically raise this value if it is too low when you add a tree particle system.
Use arrows instead of icons for panel opening: does what it says on the tin. Can help reduce visual noise, but to be honest, I'm probably going to remove this setting soon.
N-panel category: The name of the category in the N-panel to place the Alpha Trees interface.