Mentha (mint) is a genus of about 25 species (and many hundreds of varieties) of flowering plants in the family Lamiaceae (Mint Family). Species within Mentha have a subcosmopolitan distribution across Europe, Africa, Asia, Australia, and North America. Several mint hybrids commonly occur. Mints are aromatic, almost exclusively perennial, rarely annual, herbs. They have wide-spreading underground rhizomes and erect, branched stems. The leaves are arranged in opposite pairs, from simple oblong to lanceolate, often downy, and with a serrated margin. Leaf colors range from dark green and gray-green to purple, blue, and sometimes pale yellow. The flowers are produced in clusters ('verticils') on an erect spike, white to purple, the corolla two-lipped with four subequal lobes, the upper lobe usually the largest. The fruit is a small, dry capsule containing one to four seeds. While the species that make up the Mentha genus are widely distributed and can be found in many environments, most Mentha grow best in wet environments and moist soils. Mints will grow 10â€“120 cm tall and can spread over an indeterminate sized area. Due to the tendency to spread unchecked, mints are considered invasive.[ An oil is a substance that is in a viscous liquid state ("oily") at ambient temperatures or slightly warmer, and is both hydrophobic (immiscible with water) and lipophilic (miscible with other oils, literally). This general definition includes compound classes with otherwise unrelated chemical structures, properties, and uses, including vegetable oils, petrochemical oils, and volatile essential oils. Oil is a nonpolar substance.