imparipinnately

Imparipinnately describes a leaf arrangement where a compound leaf has an odd number of leaflets. This means that at the tip of the leaf stalk, there is a single terminal leaflet, with pairs of leaflets arranged opposite each other along the rachis, or central axis, below it. This is in contrast to paripinnate leaves, which have an even number of leaflets, lacking a terminal leaflet. Examples of imparipinnately compound leaves can be found in plants like ash, walnut, and pea. The term itself derives from the Latin "impar," meaning unequal or odd, and "pinna," meaning feather or leaflet. Understanding this leaf morphology is important in botanical classification and identification, helping distinguish between different plant species based on their leaf structure. The arrangement of leaflets on a compound leaf is a key characteristic studied in plant anatomy and morphology.