pinnateja

Pinnateja is a botanical term used to describe a pinnate leaf arrangement, where a single leaf features a central axis called a rachis with multiple leaflets attached along its sides. The leaflets are typically arranged in a linear or slightly curved row, giving the leaf a feather-like appearance.

Leaves with this arrangement can be classified by the pattern of leaflets. Paripinnate, or even-pinnate, describes leaves with an even number of leaflets and no terminal leaflet. Imparipinnate, or odd-pinnate, describes leaves with an odd number of leaflets and a terminal leaflet at the end of the rachis. In some plants, the leaflets themselves are divided into smaller leaflets along secondary rachises, a condition known as bipinnate, and in rare cases tripinnate when three levels of division occur.

Pinnate leaves are common across many plant families, including Fabaceae (legumes) and Oleaceae (such as certain ashes and olive relatives), among others. The structure can maximize leaf surface area for photosynthesis while maintaining structural support and flexibility. Leaflet size, shape, and the length of the rachis vary widely among species, influencing factors such as shade tolerance and drought resistance.

In botany, pinnateja is used to describe morphology rather than to identify a specific species. The term helps distinguish leaf architecture and is frequently noted in taxonomic descriptions, field guides, and horticultural literature. See also leaf arrangement, compound leaf, paripinnate, imparipinnate, bipinnate.