Planterete

Planterete is a botanical term used to describe plant structures that are cylindrical and circular in cross-section. It is most commonly applied to stems, branches, or other slender organs, indicating a round profile when viewed in cross-section perpendicular to the axis. A planterete organ has a uniform, rounded outline without flattening, ridges, or wing-like projections.

In usage, planterete is sometimes treated as synonymous with terete, the more widely used term for cylindrical cross-sections. Some floras, however, reserve planterete for a truly perfectly round cross-section and use terete more broadly for slightly less perfectly cylindrical shapes. The distinction, when made, is primarily a matter of precision in morphological description and taxonomy.

Planterete stems can occur in a wide range of plant groups, from herbaceous to woody forms, and the trait can aid in identification when cross-sectional shape is diagnostic alongside other characters. The surface texture and coloration of planterete organs can vary from smooth to pubescent, but the defining feature remains the circular, evenly rounded cross-section.

By describing a stem or other slender structure as planterete, botanists convey that the organ’s cross-sectional geometry is round and uniform, distinguishing it from angular, ridged, or flattened forms. See also terete, angular, and cross-section morphology.