Botanical Source and History.—The various linden species, bearing the above names, are all stately trees, from 40 to 100 feet in height, having a tough, fibrous bark, and a very soft, white, woody portion, yielding a very soft and light charcoal. The leaves are cordate, petiolate, alternate, serrate, and often oblique at base.
Tilia americana, Linné, has thick and smooth leaves (T. glabra of Ventenat), or has thinner leaves, softly pubescent underneath (T. pubescens of Aiton), and many-flowered cymes. The latter variety grows in the southern states, and the smooth leaved kind inhabits the United States and Canada.
Tilia heterophylla, Ventenat (T. laxifolia, Pursh; T. alba, Michaux) has bright-green leaves, smooth on upper surface but silvery-white underneath. Pennsylvania, Ohio, and Mississippi valleys, and south.
Tilia ulmifolia, Scopoli (T. microphylla, Ventenat; T. parvifolia, Ehrhart).—Leaves pale-green beneath, and smooth, except in the vein-angles, where they are pubescent. About 7-flowered cymes. This and the next species constitute the Tilia europaea of Linné.
Tilia platyphyllos, Scopoli (T. pauciflora, Hayne; T. grandiflora, Ehrhart).—Cymes 3-flowered; leaves softly pubescent on under surface, and larger than those of preceding species.
Description.—Linden flowers are borne in cymes, which are axillary, and the peduncles are partly united to a greenish-yellow, linear, leaf-like bract. The petals are 5 and whitish, or approach yellow, are oblong, or lanceolate, generally notched. The calyx is 5-parted. The stamens are numerous and hypogynous, somewhat united at their bases so as to form 5 clusters (in the last two species), while in the others the stamens are connected at their bases with a petaloid scale opposite the petal. Ovary 5-celled; style 1; stigma 5-lobed; fruit a spherical, nut-like capsule, 1-celled, and 1 or 2-seeded. When fresh, the odor is agreeable; when dry, faint. The taste is mucilaginous and sweetish.
Chemical Composition.—Linden flowers contain sugar, tannin, mucilaginous matter, fatty substance, wax, yellow coloring matter, and a volatile oil, to which their fragrant odor is due. Upon the leaves of the European species, Boussingault detected a sweet exudate, having the composition of Mt. Sinai manna. A glucosid, tiliacin, has been isolated from the leaves of the linden, as well as from Cirsium arvense (P. A. Latschinow, Amer. Jour. Pharm., 1890, p. 296).
Action, Medical Uses, and Dosage.—The European species (Tilia europaea) is a common domestic remedy in Europe for the relief of many nervous and catarrhal disorders. The leaves, flowers, and buds are employed, and their properties may be regarded as stimulant, lenitive, tonic, and nervine. The infusion is generally preferred, and may be given to allay irritation and restlessness, and to promote rest and sleep. The hot infusion is employed to check diarrhoea from cold, and in the various forms of colds and catarrhal conditions, while, either hot or cold, it may be used in restlessness, nervous headaches, painful and difficult digestion, and mild hysteria. The effects upon the nervous system are sometimes obtained by an enema, or bath, prepared from the flowers. The infusion is prepared from 30 or 40 grains of the flowers and 1 pint of water. It forms an agreeable vehicle for other medicines. A strong tincture may be prepared of the flowers (℥viij) and strong alcohol (Oj). Dose, 1 to 20 minims. The other species undoubtedly possess similar properties.