Onion

Hebrew: בָּצָל, bātsāl
Family: Amaryllidaceae
Scientific Name: Allium cepa

The onion is a storage organ that develops underground. The onion plant has several main parts:

A limited root system that includes a short stem (the onion’s basal plate);
Leaves are composed of an underground section—the base and sheath found in the ground —these parts become the dry onion;
The blade above ground – green onion, these leaves are also called scales. The leaves develop from the center of the onion and gradually expand.

The onion’s pungent taste is caused by enzymes and various chemical compounds found in its scales, which are released when the onion is cut.

To become a dry onion, it must undergo a curing process. This process occurs when the temperature rises and the days become longer, causing the onion blades to dry out and the onion to close. This process can be accelerated by ceasing to water the onion. Onions that are no longer watered are referred to as “sterile onions” (betzalim hasarisim) by the Mishnah.

The Mishnah also discusses “mother onions” (imahot shel betzalim) Many plants have the characteristic of creating a root system from the leaves under certain conditions. In onions, the outer leaf often develops an independent root system, creating a new onion. Connected multiple onions are called “mother onions.”

The onion is a perennial and can be left in the ground for two years. It is possible to differentiate between old and new leaves due to their color change, a difference mentioned in rabbinic literature between green and black leaves.

The onion is mentioned in the Torah as one of the foods craved by the rabble who left Egypt. In the Mishnah, the onion is mentioned in numerous places regarding the obligation of pe’ah, terumot, ma’aserot, and more. The plant was domesticated in Southeast Asia.

Kilei zera’im & kilei hakerem (interplanting mixed species – annuals & grapevines): Since onions are classified as vegetables, they should be distanced from other edible annuals and grapevines.

Sharpness: The onion is mentioned as a sharp plant (vis-à-vis imparting a sharp flavor in meat or milk or for non-kosher meat).

Shemitah (Sabbatical year): The onion is a vegetable that can be preserved in the ground even after it dries. If it dried completely before Rosh Hashanah and was only harvested after Rosh Hashanah, it is considered a sixth-year vegetable and thus obligated in terumot and ma’aserot, and not as a vegetable with kedushat shevi’it (which are not thus obligated).

Terumot and ma’aserot (offerings and tithes): Since the onion is a storage organ for food, its leaves often start to develop during storage (green onion). Since these leaves developed from the onion without being planted in the ground, they do not require the separation of terumot and ma’aserot.

Matanot aniyim (gifts for the poor): Because the onion ripens uniformly and can be preserved after being harvested, pe’ah (corner of the field) must be left when it is harvested from the field.

Infestation: Due to the onion’s structure, which consists of overlapping scales and is not a single unit, insects sometimes enter between the scales (especially in onions that have not undergone a full curing process or that have softened slightly). This must be taken into account before consumption.