Perilla frutescens Seeds | Perilla
LATIN NAME: Perilla frutescens
COMMON NAME: Perilla
Plant Profile
The clean, faintly cinnamon note of a good culinary leaf comes from perillaldehyde, a monoterpene aldehyde built on a p-menthane skeleton and made in glandular hairs on the leaf surface. The pathway runs through limonene: a cytochrome P450 hydroxylates the ring, the resulting alcohol is oxidised, and the aldehyde is stored in the gland until something breaks the hair. Strains that accumulate it are grown for wrapping, pickling and frying.
The two leaf colours growers know best are the green strain and the deep purple-red one, and the difference is anthocyanin. The red forms accumulate cyanidin-based anthocyanins through the epidermis and need full sun to colour properly; in shade they fade toward bronze. The pigments are water-soluble, so they bleed into a hot pan or a pickling liquor, which is why the red-leaf forms are used for colouring preserves.
Botanically the cultivated material is divided into var. frutescens, the taller form grown for seed and oil, and var. crispa, the compact form with crinkled leaves grown as a vegetable and as bedding. The flower spikes are borne in the leaf axils and at the tips, white or pale pink, and the seed is a small, round, pale brown nutlet.
The seed is the other crop. Pressed perilla seed oil is one of the richest plant sources of alpha-linolenic acid, the short-chain omega-3 fatty acid, which makes it valuable as a dietary oil and, historically, as a drying oil for paints and varnishes in East Asia. The seed is eaten toasted and ground, and the whole plant is good bee forage if it is allowed to flower. A leaf decoction is also standard in the cold and cough formulas of the region.
Science & Biotechnology
Behind the volatile there is a substantial phenolic load. Perilla leaves are rich in rosmarinic acid, the same caffeic acid ester that gives rosemary and sage their antioxidant reputation, along with luteolin and apigenin glycosides. Much of the pharmacological work on the species rests on this fraction.
Perilla has a long history in plant tissue culture. Infection with Agrobacterium rhizogenes produces hairy root cultures that grow fast without added hormones and accumulate rosmarinic acid, making them a model for producing that compound in a flask rather than a field. The genetics behind the chemotypes is being unpicked in the same way.
Uses & Benefits
In the kitchen the leaf is used fresh as a wrap for grilled food, as a flavouring in pickled vegetables, and in batter. The green form is milder and used in quantity; the red form is used sparingly for colour and for its resinous bite. Toasted seed goes into dressings and is pressed into oil. In the border, the dark forms are as useful as any coleus for a bold mass of colour.
Growing from Seed
The same species also occurs in a chemotype whose volatile fraction is led by perilla ketone, a furan-containing ketone. Wilted plants in hay or pasture are dangerous to cattle, because the compound is metabolised into a pneumotoxin that damages the lung and produces atypical interstitial pneumonia; the plant has killed stock in the southeastern United States, where it behaves as a pasture weed. Never put perilla cuttings into hay, and know what you have sown.
Perilla is a fast annual of warm soil, and seed sown into cold ground will simply sit there, so wait until the ground has warmed and the risk of frost has passed. Surface-sow, because the seed needs light, press it gently into the compost without covering it, and keep it moist.
Thin to about thirty centimetres between plants and pinch out the growing tips while they are young, which keeps them bushy and delays flowering; once the flower spikes form, the leaves toughen. Keep the red forms in full sun and water steadily, since dry spells make the leaves small and harsh. Slugs and flea beetles are worst on young seedlings, and the species self-sows enthusiastically.
Our Take
Find the chemotype you want before you commit a bed to it, because perilla is generous to the point of being a weed once it is happy. I keep a green strain for the kitchen and a dark one for colour, and let a few plants go to seed for the bees. Purple perilla is the red-leaved garden form if you want the colour without the sowing, fish mint is another leaf herb of the same Asian kitchens with a far stranger smell, and field mint is the Lamiaceae I grow beside it for a clean contrast. Sow late, pinch early, and keep it out of the hay.
Related Reading
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