trifoliolate

Trifoliolate, also written trifoliate, is a botanical term describing a leaf composed of three distinct leaflets. The leaf consists of a single petiole bearing three leaflets, typically arranged palmately with all three leaflets arising near a common point. In many trifoliolate leaves, the central leaflet is sessile or nearly so, while the lateral leaflets are borne on short stalks (petiolules).

This leaf form occurs in several plant families but is especially common in the Fabaceae. Notable examples include many clovers (Trifolium species) and other legumes that show a three-leaflet arrangement. The trifoliolate leaf can vary in leaflet shape and size across species, with margins that may be smooth or serrate.

In botanical descriptions, trifoliolate leaves are contrasted with simple leaves, compound leaves with more than three leaflets, and unifoliolate leaves (a single leaflet per leaf). The term is used both to describe the overall leaf morphology and to specify that each leaf bears three leaflets.

Etymology-wise, trifoliolate derives from Latin tri- meaning three and folium meaning leaf, with the suffix -olate forming the adjectival descriptor. The term is widely used in taxonomy and horticulture to convey a consistent three-leaflet leaf structure across a species or genus.