- explode: documentation ( source)
<?php
$groups = "<p> Item1 </p>
<p> Item 2 </p>
<p> Item 3 </p>
<p> Item 4 </p>
<p> Item 5 </p>
<p> Item 6 </p>
<p> Item 7 </p>";
$groups_arr = explode("<p>",$groups);
echo "The last element:".$groups_arr[count($groups_arr)-1];