Basil also called great basil or Saint-Joseph’s-wort, is a culinary herb of the family Lamiaceae. It is also called the “king of herbs” and the “royal herb”. The name “basil” comes from Greek (basilikón phutón), “royal/kingly plant”.
Basil is possibly native to India and has been cultivated there for more than 5,000 years. It was thoroughly familiar to the Greek authors Theophrastus and Dioscorides. It is a tender plant, best known as a culinary herb prominently featured in Italian cuisine, and also plays a major role in Southeast Asian cuisines of Indonesia, Thailand, Malaysia, Vietnam, Cambodia, Laos, and Taiwan. Depending on the species and cultivar, the leaves may taste somewhat like anise, with a strong, pungent, often sweet smell.
There are many varieties of Basil as well as several related species or species hybrids also called basil. The type used in Italian food is typically called sweet basil (or Genovese basil), as opposed to Thai basil , lemon basil and holy basil, which are used in Asia. While most common varieties of basil are treated as annuals, some are perennial in warm, tropical climates, including holy basil and a cultivar known as “African blue basil”.
The word basil comes from the Greek βασιλεύς (basileus), meaning “king”, as it has come to be associated with the Feast of the Cross commemorating the finding of the True Cross by St. Helena, mother of the emperor Constantine I. The herbalist John Gerard noted that those stung by scorpions would feel no pain if they ate basil, and Nicholas Culpeper noted of basil that it was “an herb of Mars and under the Scorpion, and therefore called Basilicon”, relating it to basilisk. The Oxford English Dictionary quotes speculations that basil may have been used in “some royal unguent, bath, or medicine”. Basil is still considered the “king of herbs” by many cookery authors.
Basil is most commonly used fresh in recipes. In general, it is added at the last moment, as cooking quickly destroys the flavor. The fresh herb can be kept for a short time in plastic bags in the refrigerator, or for a longer period in the freezer, after being blanched quickly in boiling water. The dried herb also loses most of its flavor, and what little flavor remains tastes very different, with a weak coumarin flavor, like hay.
Basil is one of the main ingredients in pesto—a green Italian oil-and-herb sauce.
The most commonly used Mediterranean basil cultivars are “Genovese”, “Purple Ruffles”, “Mammoth”, “Cinnamon”, “Lemon”, “Globe”, and “African Blue”. The Chinese also use fresh or dried basils in soups and other foods. In Taiwan, people add fresh basil leaves to thick soups. They also eat fried chicken with deep-fried basil leaves. Basil (most commonly Thai basil) is commonly steeped in cream or milk to create an interesting flavor in ice cream or chocolates (such as truffles). The leaves are not the only part of basil used in culinary applications, the flower buds have a more subtle flavor and they are edible.
Several other basils, including some other Ocimum species, are grown in many regions of Asia. Most of the Asian basils have a clove-like flavor that is, in general, stronger than the Mediterranean basils. The most notable is the holy basil or tulsi, a revered home-grown plant in India and Nepal.
Lemon basil has a strong lemony smell and flavor very different from those of other varieties because it contains a chemical called citral. It is widely used in Indonesia, where it is called kemangi and served raw, together with raw cabbage, green beans, and cucumber as an accompaniment to fried fish or duck. Its flowers, when broken up, are a zesty salad condiment.
The various basils have such different scents because the herb has a number of different essential oils that come together in different proportions for various breeds. The strong clove scent of sweet basil is derived from eugenol, the same chemical as actual cloves. The citrus scent of lemon basil and lime basil reflects their higher portion of citral, which causes this effect in several plants including lemon mint, and of limonene, which gives actual lemon peel its scent. African blue basil has a strong camphor smell because it contains camphor and camphene in higher proportions. Licorice basil contains anethole, the same chemical that makes anise smell like licorice, and in fact is sometimes called “anise basil.”
Other chemicals that help to produce the distinctive scents of many basils, depending on their proportion in each specific breed, include:
- linalyl acetate
- fenchyl acetate
- methyl eugenol
- methyl chavicol
Based on chemical content, basils can be divided into four groups:
- French; Ocimum basilicum, contains lower amounts of phenols
- exotic; contains methyl chavicol (40–80%)
- methyl cinnamate – ether 90%
Most culinary and ornamental basils are cultivars of the species Ocimum basilicum, but other species are also grown and there are many hybrids between species. Traditionally a green plant, some varieties, such as ‘Purple Delight’ have leaves that appear purple.
Basil grows between 30–130 cm (12–51 in) tall, with opposite, light green, silky leaves 3–11 cm (1.2–4.3 in) long and 1–6 cm (0.39–2.36 in) broad. The flowers are small, white in color and arranged in a terminal spike. Unusual among Lamiaceae, the four stamens and the pistil are not pushed under the upper lip of the corolla, but lie over the inferior lip. After entomophilous pollination, the corolla falls off and four round achenes develop inside the bilabiate calyx.
Basil is sensitive to cold, with best growth in hot, dry conditions. It behaves as an annual if there is any chance of a frost. However, due to its popularity, basil is cultivated in many countries around the world. Production areas include countries in the Mediterranean area, those in the temperate zone, and others in subtropical climates.
In Northern Europe, Canada, the northern states of the U.S., and the South Island of New Zealand it will grow best if sown under glass in a peat pot, then planted out in late spring/early summer (when there is little chance of a frost). Additionally, it may be sown in soil once chance of frost is past. It fares best in well-drained, sunny exposure.
Although basil grows best outdoors, it can be grown indoors in a pot and, like most herbs, will do best on a sun-facing windowsill. It should be kept away from extremely cold drafts, and grows best in strong sunlight, therefore a greenhouse or row cover is ideal if available. It can, however, be grown even in a basement, under fluorescent lights.
If its leaves have wilted from lack of water, it will recover if watered thoroughly and placed in a sunny location. Yellow leaves towards the bottom of the plant are an indication that the plant has been stressed; usually this means that it needs less water, or less or more fertilizer.
In sunnier climates such as Southern Europe, the southern states of the U.S., the North Island of New Zealand, and Australia, basil will thrive when planted outside. It also thrives over the summertime in the central and northern United States, but dies out when temperatures reach freezing point. It will grow back the next year if allowed to go to seed. It will need regular watering, but not as much attention as is needed in other climates.
Basil can also be propagated reliably from cuttings with the stems of short cuttings suspended for two weeks or so in water until roots develop.
Once a stem produces flowers, foliage production stops on that stem, the stem becomes woody, and essential oil production declines. To prevent this, a basil-grower may pinch off any flower stems before they are fully mature. Because only the blooming stem is so affected, some stems can be pinched for leaf production, while others are left to bloom for decoration or seeds.
Once the plant is allowed to flower, it may produce seed pods containing small black seeds, which can be saved and planted the following year. Picking the leaves off the plant helps promote growth, largely because the plant responds by converting pairs of leaflets next to the topmost leaves into new stems.