Essential oils of Vietnam

Vietnamese cassia is mainly Cinnamomum cassia (currently accepted as C. aromaticum). It is a different species from Ceylon cinnamon (C. verum) of Sri Lanka, with thicker bark and a heavier, hotter scent.

The largest cassia area lies in the enlarged Lào Cai province, which now includes Văn Yên (formerly Yên Bái). It holds about 143,000 hectares, nearly three quarters of the national area, yielding 40,000 to 45,000 tonnes of dried bark and over 200,000 tonnes of twigs and leaves each year. Bark is peeled in two rounds, lunar months 2 to 3 and 8 to 9; autumn bark carries more oil.

Cassia oil is mainly distilled from small branches and leaves, what remains after peeling. Yên Bái leaf oil tested at about 90% trans-cinnamaldehyde; bark oil at about 93%. The Văn Yên GI specifies 4.38 to 6.07% oil in the bark.

Trà My cassia (formerly Quảng Nam, now Đà Nẵng) is a local variety known as "cao sơn ngọc quế". Its trunk bark holds 8.93 to 10.91% oil, close to twice that of Văn Yên. Its species is unsettled: some sources place it in C. loureiroi, sold internationally as "Saigon cinnamon"; the GI file names only the genus Cinnamomum.

Star anise (Illicium verum) needs the cool climate of the northern limestone mountains. Lạng Sơn has 43,370 hectares, about 70% of the national area, of which about 28,000 hectares bear fruit. Quảng Ninh has about 8,600 hectares and Cao Bằng about 4,500. The country harvests around 22,000 tonnes of dried fruit a year, second in the world after China.

The tree gives two crops. The main crop, hồi mùa, ripens around August to September, with large, thick-petalled fruit. A smaller crop, hồi tứ quý, comes in March to April.

Star anise oil is distilled from fruit and leaves. Vietnamese samples gave 90% trans-anethole in fruit oil and 87% in leaf oil. Anethole is the molecule behind the sweet, liquorice scent, and also the main constituent of European aniseed oil (Pimpinella anisum).

Japanese star anise (Illicium anisatum) is toxic and, once dried, is almost impossible to tell apart from true star anise by eye. In 2003 the US FDA warned against star anise teas after about 40 poisonings. Clear provenance comes first when buying the fruit or oil.

Cajuput (Melaleuca cajuputi) grows wild on sandy and waterlogged soils, from the central coast down to the U Minh forests; in U Minh Hạ National Park it covers almost 89% of the area.

Cajuput distilling centres on Lộc Thủy, Phú Lộc, in Huế. In 2020 Huế cajuput oil received a geographical indication. Leaves are cut mainly from March to August, the dry season, when cineole runs higher. Huế cajuput oil contains 40 to 60% 1,8-cineole; the Vietnamese Pharmacopoeia requires 45 to 60%.

1,8-cineole is also the main constituent of eucalyptus oil. Both share a cool scent, but cajuput carries extra alcohols and sesquiterpenes that make it rounder and warmer.

All three smell of lemon, but the molecules differ.

Lemongrass (Cymbopogon citratus) is grown everywhere. Oils from several regions gave 61 to 76% citral, higher in leaf than stem.

Java citronella (Cymbopogon winterianus) is grown for citronella oil, mainly in Lâm Hà, Lâm Đồng. Its scent comes from geraniol, citronellal and citronellol rather than citral, so it leans floral and grassy rather than lemony.

May chang (Litsea cubeba) grows wild and cultivated in the northern mountains: Lào Cai, Cao Bằng, Lạng Sơn, Tuyên Quang, Thái Nguyên. The oil is distilled from the fruit, and its main constituent is also citral.

Agarwood is not the wood of the tree itself but the resin the tree forms when its trunk is wounded or infected by fungi. Vietnam has five Aquilaria species, of which A. crassna is listed by IUCN as critically endangered. All Aquilaria species have been in CITES Appendix II since 2004, so international trade requires permits.

Most agarwood today comes from plantations, where resin is induced by drilling and inoculating the trunk. Hương Khê, Hà Tĩnh, has over 800 hectares planted since around 2000. In 2025 the folk knowledge of agarwood harvesting and processing in Khánh Hòa was added to the national intangible cultural heritage list. Oud oil is distilled from resinated wood at very low yields.

Pơ mu (Fokienia hodginsii) is a high mountain conifer listed by IUCN as vulnerable. In Vietnam it sits in group IIA, which restricts logging and trade. Its oil is almost entirely sesquiterpenes, mainly nerolidol (about 35%) and fokienol (about 26%), with a dry, warm woody scent. The oil is usually distilled from roots and stumps left in the ground rather than from living trunks.

African basil (Ocimum gratissimum) gives an oil rich in eugenol, 58 to 70% in Vietnamese samples, close to clove in scent. Holy basil (O. tenuiflorum), tulsi in India, gives an oil whose beta-caryophyllene and eugenol vary widely with growing area.

Cornmint (Mentha arvensis) was trialled in the north from 1958 using hybrid line 272. Vietnamese cornmint oil contains about 68 to 71% menthol, highest in the Lâm Đồng sample.

Geographical indications are granted by Vietnam's Intellectual Property Office, confirming that a product's qualities are tied to its place. For aromatic crops the file usually specifies oil content and key constituents.