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.
Herbs or shrubs with opposite or alternate exstipulate leaves and a spicate or capitate inflorescence often clothed with bright coloured scarious bracts. Perianth inferior, composed of 3 or 5 scarious coloured or herbaceous segments, which are quite free or slightly united. Stamens 3 or 5, and opposite the perianth-segments, or some multiple of that number. Fruit membranous or baccate, 1-celled, 1- or more seeded; seeds albuminous, with a hard usually shining testa. There are between 40 and 50 genera, and nearly 500 species belonging to this order. They are chiefly tropical, and we have no native representatives.