C recursive search tree directory implementation method

1. Recursively find the tree directory

 public partial class Form1 : Form
    {
        string path = @"F:\ Study documents ";// Recursively find the tree directory 
        public Form1()
        { Recursively find the tree directory 
            InitializeComponent();
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            LoadTree(path);
        }
 public void LoadTree(string path, TreeNode node=null)
        {            
string[] dirs = Directory.GetDirectories(path);// Get subdirectories 
            foreach (string dir in dirs)
            {
                  TreeNode node1 = new TreeNode(Path.GetFileName(dir));
                //TreeNode node1 = new TreeNode(dir);// All file paths 
                if (node == null)
                {
                    treeView1.Nodes.Add(node1);
                }
                else
                {
                    node.Nodes.Add(node1);
                }
 if (Directory.GetDirectories(dir).Length > 0)
                {
                    LoadTree(dir, node1);
                }
            }
        }
    }
}