Leucas

Leucas is a genus of flowering plants in the mint family, Lamiaceae. The genus comprises numerous species distributed across Africa, the Middle East, and Asia. It was historically placed in the Verbenaceae, but current classifications place it in Lamiaceae.

Members of Leucas are typically herbs or shrubs with square stems and opposite leaves. Leaves are usually simple and may be aromatic when crushed. Inflorescences are dense spikes or racemes bearing small tubular bilabiate flowers, commonly white, blue, or purple. The fruit is a schizocarp that splits into nutlets, a characteristic feature shared with many mint-family plants.

Geographic distribution and habitat vary by species. Leucas plants are native to tropical and subtropical regions of Africa and Asia, with some species extending into the Pacific. They grow in a range of environments, including open grasslands, forest margins, disturbed areas, and roadside margins, with some species adapted to drier conditions.

Uses and research encompass traditional medicine and horticulture. Several Leucas species have uses in traditional medicine in Africa and Asia, including applications for fever, cough, and inflammation. Leucas aspera is among the better-known species in Ayurvedic and Siddha practices. In addition to medicinal uses, some species are cultivated as ornamental plants. Phytochemical studies have identified essential oils and other secondary metabolites in various Leucas species. While laboratory studies have reported antimicrobial or anti-inflammatory activity for certain extracts, robust clinical evidence is lacking, and effects are species- and preparation-specific.