stigmashape

Stigmashape is a term used in botany to refer to the external geometry and surface morphology of the stigma, the pollen-receptive organ of a flower’s pistil. The term blends stigma and shape and is used informally in some morphological studies to categorize how a stigma’s outline and surface characteristics vary among species. It is not a universally formal anatomical term, and its definition may vary by author.

Typical descriptors of stigmashape cover the overall silhouette (for example, globose, cup-shaped, or elongated), curvature of the stigma head, presence and arrangement of stigmatic lobes or papillae, surface texture (glossy, rugose, or papillate), and the distribution of secretions that aid pollen adhesion. Variation in stigmashape can influence pollination dynamics because the geometry affects pollen capture efficiency, the initial contact between pollen and stigmatic surface, and the subsequent pollen-tube encounter, with potential implications for self-compatibility systems in some taxa.

In research, stigmashape is commonly assessed using microscopy and imaging techniques: light microscopy for general morphology, scanning electron microscopy for surface detail, confocal microscopy or micro-CT for three-dimensional shape, followed by geometric morphometrics to quantify shape variables. Applications include comparative morphology, taxonomy, and ecological studies of pollination, though there is no single universal schema for labeling shapes. Researchers typically supplement stigmashape with other stigma traits such as tissue organization, stigma type (wet vs dry), and papillae density to provide a fuller characterization.