Until recently (Brummitt 1992), the family comprised about 86 genera. This number has now been reduced to 35 by the removal of many genera to the Labiatae. Thus, the family currently comprises about 1150 species of trees, lianes, shrubs, and herbs occurring in tropical regions, and especially in South America (Mabberley 2008). The principal genera are Lantana L. (about 150 species), Lippia L. (about 200 species), and Verbena L. (about 200 species).
Some species, examples of which are to be found in the genera Acantholippia Griseb., Duranta L., and Lantana L., are armed with thorns.
This species forms a garden shrub or hedge in Australia and is grown as an annual in colder climates. Acute poisoning by ingestion in animals, takes the form of "pink-nose" with reddening of the muzzle and conjunctivitis, and severe gastroenteritis with death in as short a time as 3-5 days (Hurst 1942). In chronic poisoning, signs of photosensitisation appear if the animal is exposed to sunlight. One pound of dried mature leaves can produce sensitisation in a 400 lb steer. Non pigmented skin without hair shows the first evidence of the disease; pigmented skin covered with black hair may never become involved. The skin of the muzzle, ear, neck, shoulders, legs, or other parts of the body becomes yellow, swollen, hard, cracked, and painful. The skin often peels, leaving large exposed raw areas. Areas of inflammation extend to the adjacent mucous membranes of the mouth and nasal passages. Affected animals refuse food, drool saliva from the mouth, and lose weight. The skin and membranes surrounding the eyes may become affected, as well as the eyeball itself (Oakes and Butcher 1962).
The compound responsible is a polycyclic triterpenoid named lantadene A identical in structure with rehmannic acid, the active principle in Lippia. Hepatogenous photosensitisation results from liver damage by lantadene A leading to accumulation of phylloerthrin (a normal breakdown product of chlorophyll) in the blood. Phylloerythrin has photosensitising properties (Kingsbury 1964).
Morton (1962a) asserted that contact with this prickly plant often causes dermatitis in humans; and that the pounded leaves are applied as poultices.
220 species are found in tropical America and Africa.
The leaves of Lippia citriodora yield an aromatic oil used in perfumery under the name verbena oil. Verbena oil is also a name for lemongrass oil (Cymbopogon).
The dried leaves of Lippia (as well as Origanum, fam. Labiatae), and other genera enters into the composition of the spice oregano which is an ingredient of curry powder. The increased consumption of pizza has stimulated the use of oregano which was practically unknown in the United States until after World War II (Collins 1969).
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The leaf and stem have been used to make a tea in southern Africa; the leaf is variously described as having the odour of vanilla or of mint. The Zulu drink an infusion of the leaf for medicinal purposes. The plant is suspected as a cause of geeldikkop in animals (Watt & Breyer-Brandwijk 1962). However, photosensitisation has not been reported in man.
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This species has been shown experimentally to evoke photosensitisation and icterus in sheep. The symptoms were not as severe as those seen following ingestion of Tribulus terrestris L. (fam. Zygophyllaceae). Lippia pretoriensis was less toxic than Lippia rehmannii (Quin 1933, Steyn 1934, Watt & Breyer-Brandwijk 1962). See Lippia rehmannii H. Pearson below.
The feeding of this plant to sheep evokes a condition almost indistinguishable from tribulosis or geeldikkop. The condition is a hepatogenous photosensitisation. The active principles of the plant (icterogenins) causes liver damage and the accumulation of phylloerythrin (a normal breakdown product of chlorophyll) in the blood. Phylloerythrin has photosensitising properties. Photosensitisation may appear in shorn animals on the second or third day after experimental feeding with the plant (Quin 1933, Steyn 1934, Watt & Breyer-Brandwijk 1962).
In South African traditional medicine, a cloth dipped in a decoction of the plant is applied as a counter-irritant for backache, the application producing a severe and painful dermatitis (Watt & Breyer-Brandwijk 1962).
In Zulu traditional medicine, a cold infusion of the leaf is applied to inflammations of the eyeball, and a paste of the ground-up seed is appled to sores and wounds (Watt & Breyer-Brandwijk 1962).
This branching evergreen South American shrub, often grown as an ornamental, bears sharp spines capable of inflicting mechanical injury.
In West Africa, the juice from the plant is used to treat cataract and is applied to sores on children's ears. In Brazil, the triturated fresh leaf is applied to ulcers (Watt & Breyer-Brandwijk 1962).
This species can produce dermatitis (Pammel 1911).
Both Wren (1975) and Stuart (1979) record that the plant has been used in folk medicine as a vulnerary, Wren (1975) also noting that it has been used to treat sore and inflamed eyes. The fresh leaves are used as a rubefacient (Quisumbing 1951). The statement that the plant has irritant properties (Pammel 1911) is open to doubt (Watt & Breyer-Brandwijk 1962). Shelmire (1939) states that the plant can cause acute dermatitis similar to that caused by Toxicodendron. An extract of the plant produced a positive patch test reaction in one of 50 patients who had "weed dermatitis" (Shelmire 1940).
The dried aerial parts of this plant provide the traditional Chinese medicine known as ma bian cao (= Herba Verbenae), which is used in the treatment of malaria (Huang 1993).
Pammel (1911) noted that Verbena venosa can produce dermatitis.