diff --git a/Docs/README.materials b/Docs/README.materials
index df06fadb3..f6089b914 100644
--- a/Docs/README.materials
+++ b/Docs/README.materials
@@ -113,9 +113,14 @@ tree-texture : A texture to use for the trees. Typically this will contain aroun
          8 different trees in a row, duplicate 4 times. From bottom to top, the
          rows contain
          * summer textures
-         * snow texture
+         * summer snow texture
          * winter texture
          * winter snow texture
+         
+         Each tree must have space at the top. For a 512x512 texture sheet, this
+         should be 8 pixels.  Otherwise subsequent rendering results in "top hats" 
+         above trees in the distance where the trunk of the tree above in the 
+         textures sheet bleeds downwards when the mipmaps are generated.         
 
 tree-varieties : The number of different trees defined in the tree-texture
          horizontally. (default: 1)