alternate-pinnate
Botany
adjective
Having the pinnae or leaflets of a compound leaf alternate upon the midrib or petiole; (of leaf venation) consisting of a series of lateral branches arising alternately on each side of the midrib.
Origin
Mid 19th century; earliest use found in Thomas Moore (1821–1887), gardener and writer on horticulture. Perhaps after French alternati-penné; compare slightly earlier alternipinnate.