Flora of North America, Volume 22, is the first of five volumes covering monocots in North America north of Mexico. The volume comprises many groups of acquatic plants and the North American relatives of groups that have their richest number of species in the New World tropics. Included among the treatments are the rush family (Junaceae), which include important indicator species in wetland habitats, the cat-tails (Typhaceae), spiderworts (Commelinaceae), aroids (Araceae), and pondweeds (Potamogetonaceae). Thirty families are included in this volume, representing a diverse range of plant forms - from marine Zosteraceae (eel-grasses) to stately Arecaceae (palms) and the naturalised exotic Zingiberaceae (gingers), Heliconiaceae (heliconias) and Musaceae (bananas).