Perilla is an annual of the family Lamiaceae, genus Perilla, its botanical name Perilla frutescens. Though it shares the Korean word for "seed" with sesame, the two are entirely different plants: sesame belongs to the family Pedaliaceae, genus Sesamum. The square stem shows the Lamiaceae character plainly, and the same family gathers strongly aromatic plants such as basil, mint, oregano and rosemary. A mature stem reaches around 1.5 metres, and the leaf margins are toothed. Depending on purpose, the crop is divided into seed perilla, grown for the seed, and leaf perilla, grown for the leaves. Its close cousin is chajogi (shiso, 紫蘇), whose leaves run to deep purple and other colours and which differs in form and scent; it is cultivated mainly as a medicinal herb, a spice, a colourant and an ornamental. The two are near enough to hybridise naturally.

Sown in spring and setting seed in autumn, perilla is a summer crop that grows well even on rather poor ground so long as the drainage is good. Where seed is the aim, sowing in early June generally brings flowering in early September and harvest in early October. The plant's most striking trait is the accuracy of its biological clock. It reads day length so precisely that the flowering date holds almost regardless of when it was sown, and it flowers as the days shorten. Perilla under a streetlight or indoors will stand until frost without flowering, because light at night disturbs that clock and the plant loses track of the season. Leaf-perilla growing turns the principle around: lamps burned at night through the winter suppress flowering and extend the leaf harvest. For seed growers the same effect is a problem, and streetlight spill can leave a crop that never sets seed.

Perilla originates in East Asia, including the Korean peninsula. It is distributed from India through China and East Asia, and its thick seed and mildly scented leaf suit it to the table. Its seeds have been found alongside those of cucumber, melon and hemp at the sites of ancient states such as Mahan and Jinhan, evidence of a very long history of cultivation. It is thought to have grown wild around houses and in the fields from early times, and is regarded as a crop long cultivated by and particular to the Korean people. Old Korean texts record it as yuma (油麻), suimja (水荏子), im (荏) and susoma (水蘇麻); in Japanese it is egoma (荏胡麻). Korea, China and Japan alike called it jaso, while it is perilla in English, beefsteak plant in the United States, and bhanjira in India.

The earliest Korean record of its cultivation is the Nongsa jikseol (1429), after which it appears in many agricultural and cookery texts of the Joseon period. The Nongsa jikseol advises planting it at intervals of one ja (about 30 centimetres) around the grain fields in the third and fourth months to keep livestock from damaging the crop — the animals avoid the distinctive scent of the leaves and will not eat them. The names given to perilla in Joseon agricultural texts vary from book to book, most often using the characters 荏 or 麻. In the Tohoku region of Japan, a variety close to the Korean one is called jūnen (十年), a name said to come from the belief that it could add ten years to a life.

Beyond food, perilla oil was burned in lamps and applied to silk and vessels as a preservative against warping. The Donguibogam records reducing pressed perilla oil for use in silk weaving and lacquering. The property behind this is that on contact with air the oil thickens, dries hard quickly and turns yellow; perilla oil belongs with linseed and tung oil among the drying oils. It was used on paper umbrellas, and on the wooden columns of old buildings perilla oil, lacquer and dancheong painting were applied together to keep out damp and prevent warping and decay. During restoration of Bongjeongsa Geungnakjeon, the oldest wooden building in Korea, master carpenter Choi Ki-young used perilla oil for preservative treatment. Research on the conservation and dancheong of wooden cultural properties reports that unroasted raw perilla oil is preferable where a clear oil is wanted.

In Korea the seed is pressed for oil or ground to a powder, used throughout traditional cooking and in newer fusion dishes alike. Perilla powder goes most often into soups, seasoned vegetables and porridges, and lately into cream pasta, dressings and lattes. The oil is used in seasoned vegetable dishes, bibimbap and stir-fries; its high unsaturated fat content makes it unsuitable for deep frying. Perilla leaf stands with lettuce as the leading wrap vegetable and is eaten nowhere in the world but Korea; leaf kimchi and pickles are traditional foods that carried Korean tables through winters short of green vegetables. Neighbouring countries use the plant differently. Japan uses shiso (紫蘇), close to perilla leaf in shape but different in scent, fried or pickled and served with raw fish for its strong antibacterial properties. In Laos, a purple perilla leaf called pak maengda is served with rice noodles, and in Nepal and the Kumaon region of India it is known as silam or bhangira, roasted and ground with salt, chilli and tomato into a seasoning paste.

The seed is composed of roughly 43 percent fat, 18 percent protein and 28 percent carbohydrate. Alpha-linolenic acid, an omega-3 fatty acid, accounts for more than 63 percent of the fatty acids in perilla oil — the highest figure among plant oils — and among the varieties bred by the National Institute of Crop Science are some reaching around 65 percent. The leaves carry minerals such as iron, calcium and potassium, along with vitamins A and C and rosmarinic acid. The press cake left after extraction is rich in protein and is used as livestock feed and organic fertiliser, holding about 5.6 percent nitrogen, 2.5 percent phosphoric acid and 1 percent potassium.

The single most important characteristic in handling perilla oil is oxidation. Alpha-linolenic acid carries many double bonds and oxidises readily; exposure to light and oxygen in distribution or storage, or to high heat during cooking, sets oxidation going quickly, and autoxidation continues even when the oil is sealed and kept cool and dark. In storage trials by the Rural Development Administration, perilla oil held at 25°C showed a sharp rise in acid value and peroxide value from week 20 as rancidity advanced, while oil held at 4°C showed no change in either figure through week 40. Sesame oil stands in contrast, keeping better than most vegetable oils thanks to antioxidant compounds such as lignans and gamma-tocopherol. The drying-oil property that served so well on timber becomes, inside a bottle, the property that is hardest to manage. Roasting temperature, the time elapsed since pressing, and temperature through distribution therefore decide the quality of perilla oil — which is why raw perilla oil exists as a separate product category and why cold-chain distribution is recommended.

Perilla is grown mainly in China, India, Japan, Thailand and Korea, though rarely on a scale aimed at mass consumption. In Korea it ranks sixth by cultivated area — comparable to apples on area alone — and self-sufficiency has held at 50 to 60 percent since 2000. Imports arrive as seed rather than leaf, and as of 2012 almost all perilla imported into Korea came from China. Production value stood at 171.3 billion won for seed perilla in 2012 and 113.4 billion won for leaf perilla in 2011, rising steadily alongside growing meat consumption.