function tree(no)
{
    var cur = document.getElementById("img_tree_"+no);
    var div = document.getElementById("tree_"+no);
    var len = cur.src.length;
	var dir = cur.src.substr(0, len-10);

	if (cur.src.match("tree_p.png"))
	{
		cur.src = dir+"tree_m.png";
		div.style.display = "block";
	}
	else
	{
		cur.src = dir+"tree_p.png";
		div.style.display = "none";
	}
}