pruinose

Pruinose is a botanical and mycological term used to describe a surface that bears a fine, frost-like coating of crystals or waxy particles. The word derives from Latin pruinus, meaning frosted, and pruina, frost. The coating is typically white or pale bluish and can often be rubbed off with a fingertip, revealing the underlying tissue.

In plants, pruinose surfaces can occur on leaves, stems, petals, fruits, or pollen grains. The pruina is usually a crystalline or waxy layer associated with the plant’s epidermis and can affect texture, color, and light reflection. It may also influence microclimates on the surface, dew formation, or protection from UV radiation and herbivory. The presence of pruina is often reversible and can be diminished or removed by handling or environmental wear.

In fungi and lichens, spores or other reproductive structures may be described as pruinose when they carry a similar powdery cover. This feature can aid taxonomic identification because the density and appearance of pruina vary across species or groups.

Related terms describe other surface features: farinose refers to a mealy, powdery coating; glabrous means without hairs; pubescent indicates a hairy surface; glaucous denotes a bluish waxy bloom rather than a crystalline powder. Pruinose remains a descriptive character used across disciplines to note a distinctive, easily removable frosted appearance.