This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
A small order of aquatic or semi-aquatic plants with broad leaves and solitary racemose or spicate flowers. Perianth funnel-shaped, circinate when withering. Anthers turned inwards. Fruit capsular, dehiscing loculicidally.