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.
Stem destitute of central pith, not increasing by annual layers, vascular bundles irregularly scattered amongst the cellular tissue. Leaves usually parallel-veined. Seeds with 1 cotyledon. Paits of the flower generally in whorls of three.