Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.0.rc.1)
// Compass (v1.0.0.alpha.20)
// ----

#orchard .apple, .pear {
  @at-root #{selector-append(".tree", &)} {example: selector-append;}
  // Space after .tree doesn't do anything 
  @at-root #{selector-append(".tree ", &)} {example: selector-append;}
  // Space before .tree throws an error  
  //@at-root #{selector-append(" .tree", &)} {example: selector-append;}
}

SassMeister-output.css

.tree#orchard .apple, .tree.pear {
  example: selector-append;
}
.tree#orchard .apple, .tree.pear {
  example: selector-append;
}