phylotree;
$dbxref = $phylotree->dbxref_id;
// Make sure the dbxref isn't the null database. If not, then show this pane.
if ($dbxref and $dbxref->db_id->name != 'null') { ?>
  
This tree is also available in the following databases:
db_id->name . ': ' . $dbxref->db_id->description;
  if ($dbxref->db_id->url) {
    $database = l($dbxref->db_id->name, $dbxref->db_id->url, array('attributes' => array('target' => '_blank'))) . ': ' . $dbxref->db_id->description; 
  }
  $accession = $dbxref->db_id->name . ':' . $dbxref->accession;
  if ($dbxref->db_id->urlprefix) {
    $accession = l($accession, $dbxref->db_id->urlprefix . $dbxref->accession, array('attributes' => array('target' => '_blank')));
  }
  
  $rows[] = array(
    $database,
    $accession
  );
  // the $table array contains the headers and rows array as well as other
  // options for controlling the display of the table.  Additional
  // documentation can be found here:
  // https://api.drupal.org/api/drupal/includes%21theme.inc/function/theme_table/7
  $table = array(
    'header' => $headers,
    'rows' => $rows,
    'attributes' => array(
      'id' => 'tripal_phylogeny-table-references',
      'class' => 'tripal-data-table'
    ),
    'sticky' => FALSE,
    'caption' => '',
    'colgroups' => array(),
    'empty' => t('There are no database cross-references for this tree'),
  );
  
  // once we have our table array structure defined, we call Drupal's theme_table()
  // function to generate the table.
  print theme_table($table);
}