Matricaria is a genus of flowering plants in the family Asteraceae (sunflower family), placed in the chamomile tribe Anthemideae within the order Asterales. The genus contains a small number of annual herbs, commonly known as mayweeds or chamomiles, distributed primarily across temperate regions of Eurasia and widely naturalised elsewhere.
Plants in the genus have many-branched stems that range from prostrate to erect, are glabrous (hairless), and are densely leafy. The leaves are bipinnate with numerous narrow, linear leaflets. The flower heads (capitula) are semi-spherical with greenish-yellow disc florets; ray florets, when present, are white. The receptacle is distinctively tall relative to its width — roughly two to three times as high as wide — a useful identification character. Some species, such as Matricaria discoidea (pineapple weed), entirely lack ray florets.
The taxonomy of the genus has long been disputed. Several species are placed by different authorities either in Matricaria or in the closely related genus Tripleurospermum, with the distinction resting on the number of seed ribs: Matricaria species possess four or five adaxial seed ribs, while Tripleurospermum species have one adaxial and two lateral ribs.
The most economically significant member is Matricaria chamomilla (German chamomile), widely cultivated and harvested for its essential oil and dried flower heads. It has a long history of use in herbal medicine as a carminative and anti-inflammatory agent, and is an ingredient in teas, ointments, and mouthwashes. The essential oil, known as German chamomile oil or true chamomile oil, is also used in aromatherapy.
Etymology
The name Matricaria derives from the Latin matrix ("womb" or "uterus"), reflecting the plant's historical use in treating gynaecological complaints. The root is shared with mater ("mother"), and the genus name alludes to the medicinal reputation of chamomile in traditional European herbalism.
Distribution
Most Matricaria species are native to the temperate regions of Eurasia, with a natural range extending into northern and southern Africa. Matricaria occidentalis is the sole species native to North America; all other North American occurrences represent introduced populations. Several species have also become naturalised in Australia.
Ecology
Matricaria species are hardy, pleasantly aromatic annuals that typically colonise disturbed habitats: roadsides, ruderal communities, and nutrient-rich fallow land. Despite being considered weeds in agricultural contexts, they are compatible with rock gardens, herb gardens, and border plantings. The larvae of certain Lepidoptera, including the lime-speck pug (Eupithecia centaureata), use Matricaria as a larval food plant.
Cultural Uses
Matricaria chamomilla (German chamomile) has been used for centuries in European herbal medicine. Strong infusions of the dried flowers are taken as tea and are valued as a carminative (relieving gas and digestive discomfort) and anti-inflammatory. Topically, chamomile preparations are incorporated into ointments, skin lotions, and mouthwashes to treat mouth and gum infections. In aromatherapy, the essential oil distilled from M. chamomilla flower heads — variously called German chamomile oil or true chamomile oil — is distinguished from Roman chamomile oil, which is derived from the unrelated Chamaemelum nobile.
Taxonomy Notes
The circumscription of Matricaria is contested. The primary source of disagreement is where to draw the boundary between Matricaria and Tripleurospermum: the two genera are distinguished by seed-rib morphology (four or five adaxial ribs in Matricaria; one adaxial plus two lateral ribs in Tripleurospermum), but different taxonomic authorities apply these criteria differently, resulting in certain species being assigned to either genus depending on the source consulted.
