Vines are plants that cannot remain free-standing to any appreciable height. There are both herbaceous and woody vines, the latter generally referred to as lianas or lianes. Using ‘vines’ to denote all climbing plants may initially confuse some readers from lands where, with due respect for wine, ‘the vine’ is used solely in reference to grapes. Terminological confusion aside, there are still some problems determining what is a vine and what is not. These problems derive from the fact that there is no clear distinction between selfsupporting and non-self-supporting plants either ontogenetically or evolutionarily. Most vines do not require external support until they are a decimeter up to a meter or more tall. Under some conditions, normally climbing species seem to thrive in the absence of mechanical support and take on the appearance of rank shrubs or treelets. Some vines simply lean on neighboring plants without displaying any obvious ‘adaptations’ for climbing other than a tendency towards etiolation.

Although the climbing habit has evolved many times in lineages ranging from ferns and gymnosperms to palms and legumes (see Chapter 1 by A. H. Gentry), most vines share a suite of morphological, anatomical, and physiological characteristics. These shared, and primarily derived, characteristics are the primary focus of this volume but variations among climbing plants are also given due consideration.