Cloverleaf

Cloverleaf is a term used across disciplines to describe distinct concepts that share a characteristic clover-like pattern. Notable usages include botany, civil engineering, and molecular biology.

In botany, a cloverleaf is a leaf that consists of three leaflets (a trifoliate leaf) arranged palmately at the end of a common petiole. The term is most commonly associated with clover species in the genus Trifolium, such as white clover (Trifolium repens) and red clover (Trifolium pratense). The leaflets are typically rounded or heart-shaped and may have small stipules at the base. The trifoliate arrangement is a common trait among many plants beyond true clover, and the shape has inspired the name in other contexts.

In civil engineering, a cloverleaf interchange is a highway interchange design that uses four large loop ramps to connect two perpendicular highways, allowing all turning movements without left-turn signals. The resulting pattern resembles a four-leaf clover. While the design can be space-efficient and enable smooth traffic flow in certain situations, it requires substantial land area and can create weaving conflicts near the ramps. Many examples have been modified with partial cloverleaf configurations or replaced by more modern designs such as folded-diamond or stack interchanges as traffic volumes increase.

In molecular biology, the cloverleaf model refers to the classic secondary structure of transfer RNA, depicted as a cloverleaf with four arms: the acceptor stem, the D arm, the anticodon arm, and the TψC arm. This representation aided early understanding of tRNA folding and function before three-dimensional structures were fully elucidated.