DOMElement: td vs. th

I'm trying to parse a string containing an HTML table using the builtin DOM classes and running into an odd problem. Here's what I'm doing: $dom = new DOMDocument(); $dom->loadHTML($str); $tables = $dom->getElementsByTagName("table"); $rows = $tables->item(0)->getElementsByTagName('tr'); foreach($rows as $row){ foreach($row->childNodes as $node) // stuff } This gives me the row elements in order and access to their contents. The weird part is $node always appears to be a td tag - even when it's a th tag in the original string (DOMElement::tagName is always "td" (as well as DOMNode::nodeName and DOMNode::localName)). The th tags definitely aren't being omitted; I still get nodes with their contents, just with the wrong tag name. Is there any way to override this behavior so that I can distinguish between td tags and th tags?