Spec. Plant. Willd. iii. 146. Cl. 14. Ord. 1. Didynamia Gymnospermia. Nat. ord. Labiatae. G. 1118. Calyx dry, nearly flat above : with the upper lip subfas-. tigiate. Corolla, upper lip somewhat arched, bifid; lower lip with the middle lobe cordate. Species 1. Melissa officinalis.2 Officinal or Common Balm. Med.

Bot. Id edit. 335. t. 119. Officinal. Melissae officinalis folia, Edin. Herba, Dub.

Balm leaves.

Syn. Melisse Citronelle (F.), Melisse (G.), Melissa (I.), Balsamina (S.).

Balm is a perennial plant, a native of the south of Europe, growing in mountainous situations, and flowering from July to September. It is cultivated in our gardens.3 The root is fibrous, and sends up annual stems, which rise about two feet high, and are branched, quadrangular, and smooth. The leaves are opposite in pairs, of a bright green colour, ribbed, deeply serrated, and cordate; the lower ones on long footstalks, and the upper nearly sessile. The flowers, which are in small axillary bunches, forming semi-whorls, stand on slender peduncles, at the base of which are small, oblong, notched, hairy bractes. The calyx is tubular and pentangular : the upper lip tridentate; the lower shorter, and cut into two acute teeth. The corolla, which is tubular, of a yellowish white colour, with the upper lip shorter, and notched, and the lower three-cleft, encloses the anthers: the seeds are four, ovate, and placed at the bottom of the calyx.

1 " Hujus olei binae guttae cum cerevisia vel vino propinatae sudores excitant Vehementes, cui fini apta medicamenta India exhibet perpauca,"-Rumphius.

Dioscoridis, bees being very fond of it.

"It was cultivated by Gerarde m 1596.

For medicinal use, the herb should be cut before it flowers.

Qualities.-The recent plant has the agreeable odour of lemons, which is lost in drying; and an austere, slightly aromatic taste. In distillation with water, it yields a small portion only of a yellow essential oil, on which its odour depends. The watery infusion tastes rough; reddens slightly litmus paper; and affords with persulphate of iron a deep olive, with nitrate of silver a deep brown, and with acetate of lead a copious greenish-white precipitate.

Medical properties and uses.-Balm is stimulant, stomachic, and diuretic. It was formerly prized as a corroborant, in nervous affections; but it is now used only in infusion, as a diluent in fevers.