help with first time php

[pooker]

here is the basic code

$dir = opendir('./mangareader');
while($folder = readdir($dir) ){
if (is_dir($folder) ) {
?>
<option value='1'><? echo $folder ?></option>
<?
}
}
closedir($dir);
?>

I just want it to return the folder name, is_dir does not do that

Like in mangareader there is a bunch of scripts and only a few folders I just want it to return the folder name in the dropdown menu,

Could someone please help?