Early season Thai basil
|Species||O. basilicum var. thyrsiflora|
|Cultivar group||Thai basil|
Thai basil, or Asian basil (húng quế in Vietnamese) is a type of sweet basil native to Southeast Asia that has been cultivated to provide distinctive traits. Its flavor is more stable under high or extended cooking temperatures than that of sweet basil. Thai basil exhibits small, narrow leaves and purple stems, with a mauve (pink-purple) flower. One cultivar commonly grown in the United States is 'Queen of Siam'.
Nomenclature and taxonomy 
Sweet basil, Ocimum basilicum (O. basilicum), has multiple cultivars. Thai basil, or O. basilicum 'Horapha', grows to 45 cm (1.48 ft) in height, and has purple-flushed, lance-like leaves with a sweet licorice scent.
The word Ocimum is derived from the Greek word meaning "to smell", which is appropriate for most members of the plant family Lamiaceae, also known as the mint family. Like other plants in the mint family, Thai basil features a square stem, and the leaves always grow in pairs, opposite each other and at 90 degree angles from the previous pair of leaves. With over 40 cultivars of basil, this abundance of flavors, aromas and colors leads to confusion when identifying specific cultivars. For a detailed comparison, see Purdue University's O. basilicum research and Sunland Herb's anecdotal descriptions of basil, based on four historical resources.
Three types of basil are commonly used in Thai cuisine. Thai basil is the cultivar most often used for Asian cooking in Western kitchens. The English common name is Thai basil, but in Thai kitchens, the plant is called bai horapha or simply horapha (Thai: โหระพา). Thai holy basil, also called bai gka-prow or kraphao, which may be the basil Thai people love most, is a variety of Ocimum tenuiflorum (Thai: กะเพรา). The third species of basil found in Thai cooking is the least used, and has undertones of lemon in both scent and taste. Thai lemon basil is called bai maeng-lak or simply maenglak (Thai: แมงลัก).
Basil is used in several different Asian cultures. Thai holy basil is a variety of tulasi, which is worshiped in India and is also often called "holy basil". Both Thai holy basil and tulasi have smaller, softer, slightly hairy leaves and an aroma akin to that of cloves. In Vietnam, the most common basil cultivar with purple stems is called cinnamon basil; its name describes its flavor and scent. The Vietnamese cinnamon basil was known as húng quế (lit. "cinnamon basil").
Culinary uses 
Although Vietnamese, Cambodians, and Laotians also use the Asian varieties of basil in their cuisines, the purple-stemmed, licorice-flavored leaves have come to be identified as Thai basil. It may be mistakenly called anise basil or licorice basil, but it is different from the Western strains bearing these same names. Horapha leaves are a frequent ingredient in Thai green and red curry (แกงเผ็ด), while the basil used in Thai drunken noodles, and Thai chicken/pork/seafood with basil leaf is kraphao (Thai holy basil). Thai basil is also an important ingredient in the very popular Taiwanese dish, sanbeiji (three cup chicken). Used as a condiment, a plate of raw Thai basil leaves is often served as an accompaniment to phở (Vietnamese-style noodle soup) so each customer can season it to taste with the anise-flavored leaves.
See also 
|Wikimedia Commons has media related to: Ocimum basilicum thyrsiflorum|
- Frances Hutchinson (2003). "Garden Herbs". The Gardener's Handbook. p. 237. Text " Fog City Press " ignored (help)
- Madalene Hill, Gwen Barclay, Jean Hardy (1987). Southern Herb Growing. Shearer Publishing. p. 68.
- "Classification for Kingdom Plantae Down to Species Ocimum basilicum L.". USDA.
- "LAMIACEAE (formerly LABIATAE) - The Mint Family". The Seed Site.
- Loha-Unchit, Kasma (1995). It Rains Fishes (Legends, Traditions and the Joys of Thai Cooking). Pomegranate Artbooks. p. 93. ISBN 0876543565. OCLC 31865230.
- Adventures in Thai Cooking and Travel
- Loha-Unchit, Kasma (1995). It Rains Fishes (Legends, Traditions and the Joys of Thai Cooking). Pomegranate Artbooks. p. 94. ISBN 0876543565. OCLC 31865230.
- Loha-Unchit, Kasma (1995). It Rains Fishes (Legends, Traditions and the Joys of Thai Cooking). Pomegranate Artbooks. p. 92. ISBN 0876543565. OCLC 31865230.
- Loha-Unchit, Kasma (1995). It Rains Fishes (Legends, Traditions and the Joys of Thai Cooking). Pomegranate Artbooks. p. 178. ISBN 0876543565. OCLC 31865230.