I need to use a list of taxonomy terms in a form [duplicate]

Question

I would like to bring in terms (just parents) from one taxonomy vocabulary to use as options in a form but I can't seem to pull them in. I thought taxonomy_vocabulary_machine_name_load would work but I can't seem to get the terms to show up.

  $topic_options = array();
  $name = 'web_topics';
  $myvoc = taxonomy_vocabulary_machine_name_load() as $name => $vocabulary;
  $tree = taxonomy_get_tree($myvoc->vid);
  foreach ($tree as $term) {
    $topic_options[$name] = $vocabulary->name;
  }