Tagetes

''Tagetes'' () is a genusSoule, J. A. 1996. Infrageneric Systematics of Tagetes. Pgs. 435-443 in Compositae: Systematics, Proceedings of the International Compositae Conference, Kew 1994, Vol. I, Eds. D.J.N. Hind & H.J. Beentje. of annual or perennial, mostly herbaceous plants in the family Asteraceae. They are among several groups of plants known in English as marigolds. The genus ''Tagetes'' was described by Carl Linnaeus in 1753.

These plants are native to Mexico, growing naturally since Mexico's valley down to the south and even reaching several other Latinamerican countries, but some species have become naturalized around the world. One species, '' T. minuta'', is considered a noxious invasive plant in some areas.

Description

''Tagetes'' species vary in size from 0.1 to 2.2 m tall. Most species have pinnate green leaves. Blooms naturally occur in golden, orange, yellow, and white colors, often with maroon highlights. Floral heads are typically (1-) to 4–6 cm diameter, generally with both ray florets and disc florets. In horticulture, they tend to be planted as annuals, although the perennial species are gaining popularity. They have fibrous roots.

Depending on the species, ''Tagetes'' species grow well in almost any sort of soil. Most horticultural selections grow best in soil with good drainage, and some cultivars are known to have good tolerance to drought.

Nomenclature

The Latin ''Tagētes'' derives from the name of the Etruscan Tages, born from the plowing of the earth. It likely refers to the ease with which plants of this genus come out each year either by the seeds produced in the previous year, or by the stems which regrow from the stump already in place.

The common name in English, marigold, is derived from ''Mary's gold'', a name first applied to a similar plant native to Europe, ''Calendula officinalis''.

The most commonly cultivated varieties of ''Tagetes'' are known variously as African marigolds (usually referring to cultivars and hybrids of ''Tagetes erecta''), or French marigolds (usually referring to hybrids and cultivars of '' Tagetes patula'', many of which were developed in France). The so-called signet marigolds are hybrids derived mostly from '' Tagetes tenuifolia''.

Cultivation and uses

Depending on the species, marigold foliage has a musky, pungent scent, though some varieties have been bred to be scentless. It is said to deter some common insect pests, as well as nematodes. ''Tagetes'' species — notably '' T. patula'' — are hence often used in companion planting for tomato, eggplant, chili pepper, tobacco, and potato. Due to antibacterial thiophenes exuded by the roots, ''Tagetes'' should not be planted near any legume crop.Soule, J. A. 1993. Biosystematics of ''Tagetes'' (Compositae). Ph.D. Dissertation, University of Texas. Some of the perennial species are deer-, rabbit-, rodent- and javelina or peccary-resistant.

'' T. minuta'' (khakibush or huacatay), originally from South America, has been used as a source of essential oil for the perfume and industry known as tagette or "marigold oil", and as a flavourant in the food and tobacco industries. It is commonly cultivated in South Africa, where the species is also a useful pioneer plant in the reclamation of disturbed land.

The florets of ''Tagetes erecta'' are rich in the orange-yellow carotenoid lutein