Perilla
Perilla is a genus of annual herbs in the mint family Lamiaceae, native to the Himalayas and Southeast Asia, consisting primarily of the species Perilla frutescens, an upright bushy plant that grows 1–3 feet (0.3–1 m) tall with aromatic, ovate leaves and white flowers.[1][2] The genus Perilla includes two main varieties of P. frutescens: var. frutescens, which is cultivated as a vegetable and oil crop with broad, green to purple leaves, and var. crispa, featuring crinkled leaves used for medicinal and nutritional purposes.[3] These plants are erect, freely branching herbaceous annuals with square stems that can be green or purple, and they produce small, nettle-like flowers in terminal spikes from late summer to fall.[4] Native to eastern Asia, Perilla has been widely naturalized and sometimes considered invasive in parts of North America due to its prolific self-seeding.[1][5] Perilla frutescens holds significant culinary value in Asian cuisines, where its leaves—known as shiso in Japan and kkaennip in Korea—are used fresh, pickled, or as wraps for meats and rice, imparting a musky mint flavor enhanced by compounds like perillaldehyde.[3] The seeds yield perilla oil, rich in α-linolenic acid (53–62%), which is employed in cooking, as a condiment, and in baked goods or beverages.[3] Nutritionally, the leaves are high in β-carotene (7,565 μg/100 g raw) and provide substantial vitamins, minerals, and protein (22.7 g/100 g in seeds), contributing to its role as a food homologous to medicine.[3] Medicinally, Perilla has a long history in traditional Chinese medicine for treating colds, asthma, and inflammation, with modern research supporting its anti-inflammatory, anticancer, and gut microbiota-modulating effects, particularly from perilla oil in improving quality of life for cancer patients.[3] Despite these benefits, the plant is toxic to livestock when ingested in large quantities, posing risks to cattle and horses in pastoral areas.[4] Economically, Perilla is valued for oil production, nutraceuticals, and ornamental use, with potential for expansion into non-Asian markets, though cultivation challenges like seed shattering persist.[3][1]Description
Physical characteristics
Perilla frutescens is an annual herbaceous plant belonging to the Lamiaceae family, characterized by its erect, branching habit and square stems that are typical of the mint family. The stems are usually green but can appear purple in certain varieties, covered in fine hairs, and support a height ranging from 0.6 to 1.8 meters, though plants often average around 0.6 to 1 meter in optimal conditions.[2][6][7] The leaves are arranged oppositely along the stems, ovate to broadly ovate in shape, measuring 7 to 15 cm in length and 5 to 10 cm wide, with coarsely serrated margins and a pointed tip. Coloration varies significantly by variety, from vibrant green in standard forms to deep purple-red in anthocyanin-rich types, which exhibit higher levels of pigments like malonylshisonin and shisonin responsible for the red hues. When crushed, the leaves emit a strong minty aroma attributed to essential oils such as perillaldehyde and limonene.[2][8][9] Flowers are small, measuring about 3-5 mm, with a two-lipped, bell-shaped corolla that ranges from white to pale purple, arranged in terminal spike-like inflorescences up to 15 cm long. These spikes emerge from the upper stems and leaf axils, blooming from late summer through fall. The plant produces small, round seeds, approximately 1 to 1.5 mm in diameter, enclosed in a persistent calyx; they are dark brown to gray-brown and contain high oil content, varying by variety with red types often showing elevated phenolic compounds.[2][6][7][9]Habitat and distribution
Perilla species, particularly Perilla frutescens, are native to subtropical and temperate regions of East Asia, spanning the mountains of China, the Himalayas, India, Japan, Korea, and Vietnam.[1][10][11] The plant's natural range extends from northeast India eastward to southern and eastern China, including elevations up to 1,200 meters in mountainous areas.[11][10] In its native habitats, P. frutescens thrives in moist, well-drained soils with a preference for light to medium loamy textures and a pH range from mildly acidic to basic.[12][1] It tolerates partial shade to full sun, often growing in forest edges, grasslands, hillsides, and disturbed sites such as roadsides and ditches.[4][13] Wild forms are commonly found in these transitional environments, where the plant's adaptability to varying light and moisture levels supports its persistence.[1][14] Today, P. frutescens is cultivated worldwide for its culinary and medicinal uses, with naturalized populations established beyond its native range.[5] It has become invasive in parts of North America, particularly the eastern United States from Connecticut to Florida, where it spreads via seed dispersal into natural and disturbed areas.[15][13] In Europe, escapes from cultivation have led to naturalization in regions like Belgium and Bosnia and Herzegovina, often along roadsides and waste grounds due to prolific seed production and dispersal.[16][17] Ecologically, P. frutescens plays a role in attracting pollinators, with studies showing high visitation rates by insects such as honeybees, which account for up to 93% of floral visitors during blooming.[18] Its allelopathic properties, mediated by compounds like perilla ketone, inhibit the growth of nearby weeds and competing plants, potentially aiding its invasiveness in non-native habitats.[19][14]Taxonomy
Classification
Perilla is classified within the kingdom Plantae, phylum Tracheophyta, class Magnoliopsida, order Lamiales, family Lamiaceae, subfamily Nepetoideae, tribe Elsholtzieae, and genus Perilla.[20][21] This placement situates the genus among other aromatic herbs in the mint family, known for their square stems and essential oil production.[21] The genus is distinguished from related genera such as Mentha and Ocimum by a unique combination of morphological and chemical traits, including square stems typical of Lamiaceae, anisocytic stomata on leaf surfaces, and the presence of perillaldehyde as a dominant compound in its essential oils.[22][23] These features contribute to Perilla's distinctive fragrance and ecological adaptations, setting it apart within the tribe Elsholtzieae.[20] Phylogenetically, Perilla is closely related to other herbaceous genera in the Lamiaceae, with molecular studies supporting the monophyletic status of the genus and identifying P. frutescens as its core species. The genus name "Perilla" derives from the Latin word pera, meaning "bag," referring to the shape of the fruiting calyx.[2]Species and varieties
The genus Perilla in the family Lamiaceae is recognized as containing a single widely cultivated species, Perilla frutescens (L.) Britton, along with a few wild diploid relatives native to eastern Asia.[24] This primary species is an annual herb native from the southern Russian Far East to Pakistan and the Indian subcontinent, with extensive cultivation and introduction worldwide.[25] Some taxonomic treatments recognize certain wild forms as separate diploid species, while others classify them as varieties of P. frutescens.[21][24] P. frutescens exhibits significant infraspecific variation, classified into several varieties based on leaf color, morphology, and use. The variety P. frutescens var. frutescens features green leaves and is primarily cultivated for its seeds, known as deulkkae in Korean cuisine, where the oil-rich seeds are used for flavoring and pressing into edible oil.[26] In contrast, P. frutescens var. crispa (Thunb.) H. Deane produces purple-red leaves with crinkled edges and is the form commonly referred to as shiso in Japanese culinary traditions, valued for its aromatic foliage. Another recognized variety, P. frutescens var. hirtella (Nakai) Makino, is distinguished by its hairy leaves and stems, though it is less commonly cultivated. Historical synonyms for aspects of P. frutescens include P. nankinensis Decne., often associated with seed-producing forms, and Ocimum frutescens L., an early basionym from Linnaeus.[25] Wild relatives include Perilla citriodora (Makino) Nakai, a diploid species found in eastern Asia, which differs from the cultivated tetraploid P. frutescens in chromosome number and essential oil composition but shares morphological similarities; it is sometimes treated as a synonym of var. hirtella.[24] Other less recognized taxa, such as P. japonica (Hassk.) Nakai, are now treated as synonyms of P. frutescens var. frutescens.[27] P. chinensis (L.) Britton has been historically used but is largely synonymous with cultivated variants of P. frutescens, particularly in Chinese contexts.[28] Additional wild species reported in taxonomic surveys include P. setoyensis G. Honda and P. hirtella Nakai, both diploid and restricted to eastern Asia, with P. hirtella representing a hairy wild form.[24] Infrageneric variation within Perilla frutescens is further delineated by chemotypes, defined by dominant compounds in their essential oils, which influence aroma and potential applications. Common chemotypes include the perillaldehyde (PA) type, prevalent in leaf-focused cultivars like shiso, and the citral (C) type, found in some wild or seed-oriented forms, with genetic control determining the biosynthetic pathways for these monoterpenoids.[29] Other chemotypes, such as those rich in elsholtziaketone (EK) or piperitenone (PT), occur less frequently and are linked to specific regional accessions.[30]| Variety | Leaf Characteristics | Primary Use | Native/Cultivated Range |
|---|---|---|---|
| P. frutescens var. frutescens | Green, smooth | Seeds (deulkkae oil) | East Asia, introduced globally[26] |
| P. frutescens var. crispa | Purple-red, crinkled | Aromatic leaves (shiso) | Japan, cultivated in Korea, China |
| P. frutescens var. hirtella | Green, hairy | Ornamental/wild | Japan, Korea[31] |