Holy Basil - [Tulsi (india); Krapao (Thai); Humong Basil (Calif.); Hot Basil Ocimum sanctum (Mint family)]

In India this basil is highly revered and used for religious purposes and in Ayurvedic medicine. I Thailand it is used as a culinary herb, but unlike other basils it is always cooked, not used raw or just warmed. There are two basic varieties, one with purplish green leaves and purple stems (called purple), the other is all green (called white). Unlike other basils the leaf margins are strongly serrated, the leaves are slightly fuzzy and the stems are definitely fuzzy. It has very poor keeping qualities, if it's really fresh when you buy it you may get 2 days. Holy Basil has a strong flavor that is sharper and more minty than other basils, and with a hint of camphor. Details and Cooking.. Subst: Mint, Perilla, a mix of Thai Purple Basil and Mint.

Italian Basil - [Sweet Basil, Genovese Basil, Mediterranean Basil, Ocimum basilicum (Mint family)]

This Basil is universally called for in European and American recipes. Formerly it was very easy to grow in season but lately it often falls victim to fusarium wilt, caused by a soilborne fungus, Fusarium oxysporum f. sp. basilicum.

Sweet Basil has decent keeping properties (almost a week if treated well). It is more aromatic and less sharp than Thai Purple Basil but the two can be used interchangeably in a pinch. I've even used Thai Purple Basil to make Italian Pesto because I can get piles of it cheap at ethnic groceries while Italian Basil can cost several dollars an ounce in the supermarkets. Details and Cooking.

African Basil - [Wild Basil, Ocimum canum, also Ocimum kilimandscharicum]
A perennial basil grown in Africa and recently brought to Europe but not yet popular in North America. It's flavor is strong but less pleasant than that of Thai Purple Basil. In Europe it is being used to produce interesting hybrids with Mediterranean basil. From the ads on the Internet I gather O. canum has widespread medicinal and magical uses.

Thai Lemon Basil - [Bai Maeng-lak (Thai); O. citriodorum]
This is one of the basils that has become common in Southern California, often labeled "Thai Basil". It is characterized by a citrus fragrance, smaller light green pointed leaves and a relatively light flavor - and bad keeping properties (maybe 3 days if you take good care of it). It often alternates with Thai Purple Basil in the markets. The stronger more aromatic flavor of the purple is better for most Thai cooking while the Lemon Basil is used mainly for salads and some soups. Details and Cooking

Thai Purple Basil - [Bai Horapha (Thai); Hung Que (Viet); Anise Basil; Ocimum basilicum]

Now quite common in Southern California, this basil has good flavor and reasonable keeping properties (almost a week if treated well). In general the leaves are dark green with only a hint of purple, and the stems are distinctly purple but there are also all-green varieties. Of the Asian basils, this one is closest to Italian Basil but is sharper and slightly sweeter in taste. They can substitute for each other in a pinch. Details and Cooking.

Basil Seeds - [takmaria, tukmaria sabja, subja, falooda (India); Ocimum basilicum]

Some basil seeds have a coating on them that becomes gelatinous when soaked overnight in water. This feature is exploited in a number of drinks throughout South and Southeast Asia, particularly India and Thailand. The seeds provide texture and do not have much of a basil flavor. Basil seeds are also used in traditional and Ayurvedic medicine. As the photo specimens show, these seeds are very small, 0.05 inch, a little over 1 mm.

Tree Basil - [Wild Basil, Ocimum gratissimum]

This basil grows wild in parts of Africa, Southeast Asia and Hawaii. The leaves have a very intense flavor of cloves, so intense just a couple of leaves in the pot is sufficient. It is said to be particularly good for use with meats cooked in red wine. Photo by Forest & Kim Starr distributed under license Creative Commons Attribution 3.0 - attribution required, notification desired at starrimages@hear.org.