Tragacantha

a subgenus of the genus Astragalus of the family Leguminosae. The plants are strongly branched thorny shrubs that sometimes form mats. The leaves are even-pinnate, with tiny leaflets and a persistent, hardening axis. The variously colored flowers are clustered in groups of two to 15 in the leaf axils. The fruit is a pod, which is usually thick-haired and single-seeded.

There are approximately 240 species, distributed mainly in the mountains of Western and Middle Asia. A few species occur in Southern Europe, North Africa, and northwestern India. The USSR has about 70 species in the Crimea, the Caucasus, and Middle Asia. The plants occur, often forming thickets, in the steppe zone of mountains on arid rocky and gravelly areas of mountain plateaus and slopes.

The wood contains the gum tragacanth, which is used in the pharmaceutical industry in the preparation of pills, tablets, and lozenges and in the textile industry as a dye thickener for calico printing and for sizing fabrics and lace. In the USSR the most important gum-bearing species are T. piletocladus and T. densissimus; in the countries of Southwest Asia T. gummifer, T. adscendens, and T. pycnocladus are the most valuable gum-bearers of the subgenus.