Trachyspermum

Trachyspermum is a small genus in the Apiaceae family, most commonly represented by a single cultivated species, Trachyspermum ammi. It is widely known for its seeds, ajwain or carom seeds, and is native to the Indian subcontinent and parts of the Middle East. Taxonomically, Trachyspermum ammi has also been classified under other genera, such as Carum copticum, but the name Trachyspermum ammi is widely accepted in current classifications.

The plant is an annual herb that typically reaches 30 to 60 centimeters in height. It has pinnate leaves and small white flowers arranged in umbels. After flowering, it produces small, brown, ridged seeds about 2 to 5 millimeters long. The seeds emit a strong, thyme-like aroma when crushed, a feature exploited in culinary and medicinal applications.

Culinary use centers on the seeds, which are ground or used whole to flavor breads, curries, lentil dishes, pickles, and spice blends in Indian, Persian, and other cuisines. The essential oil of ajwain is rich in thymol, with other constituents such as gamma-terpinene and p-cymene, contributing to its distinctive pungency and aroma. In traditional medicine, ajwain seeds are used as a carminative and digestive aid. As with concentrated essential oils, ajwain should be used in moderation and properly diluted when employed for external applications.