臺灣水韮(Isoetes taiwanensis DeVol)之葉片具有氣孔,分佈在葉尖端較多,愈靠近葉基部數量愈少。暴露空氣中之葉片,其氣孔是張開的;而沈浸在水中之部份的葉片,其氣孔是關閉的。氣孔之開閉係由保衛細胞兩旁之輔助細胞(subsidary cells)所控制。原沈浸水中之葉片,暴露在空氣中之後兩小時,氣孔即完全張開;而再度沈浸在水中之氣孔,其關閉則費時甚長,這種快開慢關之特性,有助於臺灣水韮對環境的適應。
The leaves of Isoetes taiwanensis DeVol have stomata, It is observed that the stomata do have some funtions. The stomata are closed when the leaf submerged; and open when the leaf emerged whether day or night. After 2 hours the leaf exposed to air, the open ratio of stomata is 100%; but when the leaf submerged again, the closed ration of stomata is only about 85% after 10 hours.We find that the movement of guard cells are controlled by the subsidary cells from S.E.M. and paraffin method's observations.