glauca

Glauca is a feminine Latin adjective used in biological nomenclature as an epithet describing a glaucous appearance—a bluish-green, gray, or waxy-coated surface. The term derives from Latin glauca, itself from the Greek glaukos, meaning blue-green, pale gray, or gleaming. In taxonomy, glauca signals a characteristic surface trait rather than a specific lineage.

In plant nomenclature, glauca is widely applied across genera to denote glaucous foliage, fruit, or stems. Notable examples include Eucalyptus glauca, commonly known as blue mallee, and Acacia glauca, frequently referred to as blue wattle. The epithet serves as a descriptive label rather than a taxonomic clue about relatedness, and it can appear in many unrelated families.

Glaucousness results from a waxy cuticular layer or surface bloom that can range from powdery to waxy. This coating often helps reduce water loss, reflect excess light, and may provide some protection against herbivory or pathogens. The glaucous coating can be rubbed off or worn away, sometimes revealing a greener or duller underlayer.

Outside botany, glauca can appear in zoological or other biological names to indicate a glaucous coloration in certain species, though this usage is less common than in plants. The gendered form of the epithet agrees with the genus name in Latin grammar.

See also: glaucous, list of Latin color epithets.