The order Alismatales comprises three families. The , consisting of a single....

Most members of the Alismatales order possess short stems and are rooted in mud with only the leaves visible above water level. In some species even the leaves are submerged and fail to differentiate into the familiar lamina (blade) and petiole (leaf stalk) of land plants. Succulence is characteristic of Alismatales, and air spaces may occupy 80 percent of the volume of internal tissues of the leaf and root. A potential flower cluster (inflorescence) arises as a specialized stem from the flattened vegetative stem at the juncture of a leaf base. In other groups, such as the Alismataceae, seeds are liberated only after the ovary wall disintegrates in the water. APA style: Alismatales.