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 family of marsh and water plants, chiefly insignificant weeds. Flowers small and often incomplete, parts in twos or fours. The Water Milfoil (Myriophyllum) and Mare's Tail (Hippitris) belong to this order. The only species worthy of further notice here is of very distinct and peculiar habit, as will be seen from the cut.