diff --git a/python_scripts/add_trees_to_open_street_map/tree.py b/python_scripts/add_trees_to_open_street_map/tree.py
index c2ac6fb2245c9f16dd29ef9684beef3a9772cd8f..9d00285c3574800c90b6bc88802c8968f9b03697 100644
--- a/python_scripts/add_trees_to_open_street_map/tree.py
+++ b/python_scripts/add_trees_to_open_street_map/tree.py
@@ -5,13 +5,13 @@ import kdtree
 
 @dataclass
 class Tree:
-    x: float
-    y: float
-    diameter: float
-    height: float
-    z: float = 0
-    trunk_diameter: float|None = None
-    type: str|None = None
+    x: float  # [m]
+    y: float  # [m]
+    diameter: float  # [m]
+    height: float  # [m]
+    z: float = 0  # [m]
+    trunk_diameter: float | None = None  # [cm]
+    type: str | None = None
     description: str = '?'
     source: str = '?'
     color: str = 'green'