Purdue Arboretum botanical terminology reference and learning database.
Adventitious Occurring in other than the usual place - example roots appearing on an above-ground stem Did you know? Corn produces adventitious “prop roots” above the soil that brace the tall stalk against wind.
Alternate Arranged on different sides of a stem - usually refers to leaves that appear alternately, first on one side of the stem, then on the other - not in opposing pairs Did you know? Leaf arrangement is one of the fastest winter identification clues. Maples usually have opposite leaves, while oaks and elms have alternate leaves.
Amplexicaul Clasping the stem, as in the case of the base or stipules of some leaves Did you know? Some clasping leaves form small cups around the stem that can collect rainwater and organic debris.
Areole A spot on a cactus from which a spine emerges Did you know? Areoles are unique to cacti. Every cactus spine, flower, or new shoot grows from an areole.
The Purdue Arboretum is a collaboration between the Department of Horticulture and Landscape Architecture and Administrative Operations