Basic Biology of Basil
Ocimum basilicum is an herbaceous plant originally from tropical areas such as southern Asia, including India, and Africa. In such climates, it can grow as a perennial. In much of the world, it is cultivated as an annual, however, since the plant cannot tolerate frost. Basil grows best in long days with full sun and requires consistent moisture.
Being a member of the mint family, basil has square stems. The leaves are dotted with glands containing oil comprising a number of aromatic secondary metabolites. The composition of the oil varies greatly between different cultivars. It is the oil that gives basil its distinctive, slightly mint-like smell.
Basil leaves are formed opposite to one another and are velvet green or purple, depending on the cultivar. The plants grow to about one-and-seven-tenths to four feet in height and produce white flowers in a terminal spike. Normally when cultivated as an herb, the flowers are cropped off, so the plant will keep producing leaves. The flowers set seeds that are also rich in oils. The seeds produced by a particular plant can vary greatly in their morphological characteristics and oil production. This lack of genetic uniformity can complicate the growth of cultivars from seeds. All of the members of the Ocimum basilicum group have 48 chromosomes.