Sesame seeds are tiny, oil-rich seeds used globally, sprinkled over bagels, baked into crackers, and ground into tahini paste. They are prized for their subtle, nutty flavor and high oil content, which ranges from 44 to 60% of the seed’s volume. The oil extracted from them is noted for its resistance to oxidative rancidity, giving it a long shelf life. Understanding the source of these seeds requires examining the plant from which they originate.
Identifying the Sesame Plant
The source of these seeds is an erect annual plant scientifically known as Sesamum indicum, which belongs to the Pedaliaceae family. This crop is considered one of the oldest oilseed crops known to humanity, with domestication occurring well over 3,000 years ago. While numerous wild relatives of the Sesamum genus are native to sub-Saharan Africa, the cultivated species, S. indicum, is widely believed to have originated in India. Archaeological evidence indicates that the plant was domesticated in the Indian subcontinent at least 5,500 years ago.
How the Plant Grows
The sesame plant is an annual herb that grows between two and six feet tall. Its leaves are broadly lanceolate, reaching up to five inches near the base and becoming noticeably smaller higher up the stalk. The plant produces bell-shaped, tubular flowers, which are typically white, though they can also be yellow, pink, or purple depending on the specific variety.
Cultivation thrives in hot, frost-free environments, requiring 90 to 120 days without frost to reach maturity. The optimal temperature range for growth, flowering, and ripening is between 25 and 35 degrees Celsius (77–95 degrees Fahrenheit). Although sesame is drought-tolerant due to its deep root system, it yields best in fertile, well-drained soils with a neutral pH and has a low tolerance for waterlogged conditions.
The Unique Harvesting Process
The seeds themselves develop inside four-grooved capsules or pods that form at the leaf axils along the stem of the plant. Historically, the primary challenge in harvesting sesame has been the plant’s natural tendency toward dehiscence, which is the splitting open of the seed pod upon maturity. This process causes the seeds to scatter suddenly, giving rise to the famous phrase “open sesame,” which refers to the pod bursting open.
For thousands of years, this characteristic necessitated a highly labor-intensive, two-part harvesting method. Farmers traditionally cut the stalks by hand when the base capsules began to ripen and the leaves dropped. These cut stalks were then bundled and stacked upright in the field, allowing them to dry completely and for the remaining capsules to open naturally, with the seeds collected on cloths or threshing floors beneath the bundles.
In modern agriculture, plant breeders have developed non-dehiscent or “non-shattering” varieties to allow for full mechanical harvesting. These newer cultivars retain a majority of the seeds in the capsule after drying, which significantly reduces the seed loss that occurs when combines are used, making the crop viable for large-scale, mechanized production.