Calostoma
... that mushrooms of the genus Calostoma are sometimes called "prettymouth" because of peristome tissue that appears on them when they expand?
... that mushrooms of the genus <i id="mwBFs"><b id="mwBFw"><a href="./Calostoma" id="mwBF0" rel="mw:WikiLink" title="Calostoma">Calostoma</a></b></i> are sometimes called "prettymouth" because of <a href="./Peristome" id="mwBF4" rel="mw:WikiLink" title="Peristome">peristome</a> tissue that appears on them when they expand?