Hello!
I was searching for something like this too and I wrote my own function because I didn't found anything useful :( or didn't knew how to use the "get_the_category_parents()" function...
So here it is:
<?php
function get_parent_category($id)
{
global $wpdb;
$category = $wpdb->get_results("SELECT cat_ID, cat_name, category_nicename, category_description, category_parent FROM ".$wpdb->categories." WHERE cat_ID=".$id);
if( isset($category) && !empty($category) ) :
$category_output = array();
$category_output['cat_ID'] = $category[0]->cat_ID;
$category_output['cat_name'] = $category[0]->cat_name;
$category_output['category_nicename'] = $category[0]->category_nicename;
$category_output['category_description'] = $category[0]->category_description;
$category_output['category_parent'] = $category[0]->category_parent;
return $category_output;
else :
return FALSE;
endif;
}
?>
You will use it like this for example:
<?php
if( $cat > 0 ) :
$this_category = get_parent_category($cat);
?>
<h2><?php echo $this_category['cat_name']; ?></h2>
<?php echo $this_category['category_description']; ?>
<?php endif; ?>
Hope you'll understand. You will get "cat_ID", "cat_name", "category_nicename", "category_description" and "category_parent" in the variable that you assign the results of the "get_parent_category()" function.
"get_parent_category($cat)" is the call of the function, where "$cat" is the current category_ID and is usually direct available.
Hope this works. Maybe you'll have to change it a bit, this is what I needed for my page.
Cheers, Boby!