diff --git a/content_taxonomy.module b/content_taxonomy.module
index 7136659fda47febdc2f97e04ae9d55d1f7801e62..2b3db2b43aa9f7003dee6dd0ed0e8fa9599824b5 100644
--- a/content_taxonomy.module
+++ b/content_taxonomy.module
@@ -27,6 +27,52 @@ function content_taxonomy_form_field_ui_field_edit_form_alter(&$form, &$form_sta
         '#options' => $options,
         '#default_value' => isset($tree['parent']) ? $tree['parent'] : 0,
       );
+
+      $form['field']['settings']['allowed_values'][$delta]['depth']  = array(
+        '#type' => 'textfield',
+        '#title' => t('Tree depth'),
+        '#default_value' => isset($tree['depth']) ? $tree['depth'] : '',
+        '#description' => t('Set the depth of the tree. Leave empty to load all terms.'),
+        '#element_validate' => array('_element_validate_integer_positive'),
+      );
     } 
   }
+}
+
+
+/**
+ * Implements hook_field_info_alter().
+ */
+function content_taxonomy_field_info_alter(&$info) {
+  // Use own options callback for handling additional configuration options.
+  $info['taxonomy_term_reference']['settings']['options_list_callback'] = 'content_taxonomy_allowed_values';
+
+  // Add depth option.
+  foreach ($info['taxonomy_term_reference']['settings']['allowed_values'] as $key => $values) {
+    $info['taxonomy_term_reference']['settings']['allowed_values'][$key]['depth'] = 0;
+  }
+}
+
+/**
+ * Returns the set of valid terms for a taxonomy field.
+ * Extends taxonomy_allowed_values() with the tree depth option.
+ *
+ * @param $field
+ *   The field definition.
+ * @return
+ *   The array of valid terms for this field, keyed by term id.
+ */
+function content_taxonomy_allowed_values($field) {
+  $options = array();
+  foreach ($field['settings']['allowed_values'] as $tree) {
+    if ($vocabulary = taxonomy_vocabulary_machine_name_load($tree['vocabulary'])) {
+      $max_depth = (isset($tree['depth']) && !empty($tree['depth'])) ? $tree['depth'] : NULL;
+      if ($terms = taxonomy_get_tree($vocabulary->vid, $tree['parent'], $max_depth)) {
+        foreach ($terms as $term) {
+          $options[$term->tid] = str_repeat('-', $term->depth) . $term->name;
+        }
+      }
+    }
+  }
+  return $options;
 }
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