diff --git a/my_tree.py b/my_tree.py
index 292d9c6..107f740 100644
--- a/my_tree.py
+++ b/my_tree.py
@@ -9,7 +9,8 @@ w.bgcolor('wheat')      # wheat小麦
 # 移动到起点
   # 后退
 def tree(n):
-    if n>=0:
+    if n>=50:
+        pen.pensize( n\10 )
         pen.forward(n)
         pen.right(30)
         tree(n-10)
@@ -23,5 +24,5 @@ pen.left(90)
 pen.up()
 pen.backward(150) 
 pen.down() 
-tree(50)
+tree(100)
 turtle.done()