ABSTRACT
The "asterids" comprise ten orders which resolve as a clade that is well supported by both molecular and nonmolecular characters. This chapter discusses nine orders of asterids with obligate aquatic representatives in North America. The orders are Cornales, Ericales, Gentianales, Lamiales, Solanales, Apiales, Aquifoliales, Asterales and Dipsacales. The chapter describes the etymology, synonyms, distribution, diversity, indicators, habitat, key morphology, life history, imperilment, ecology and economic importance of these families. Molecular data from a number of studies have clearly established the monophyly of Cornales, an order containing about 660 species in 40 genera. Species in the dogwood genus Cornus (Cornaceae) often are encountered in wetlands; however, their broad ecological amplitude probably is responsible for their lack of obligate wetland (OBL) status. Gentianales represent a large order of more than 14, 000 species, which are characterized by vestured pits, stipules, and glandular hairs on the stipules or petioles.
