(Pea or Bean family)
Three species, native to tropical South America, provide useful timber.
- Melanoxylon brauna
This wood is said to cause dermatitis (Hanslian and Kadlec 1966). Hausen (1970) cites Friese (1932) for an injurious effect of the wood. He described pustules and necrotising inflammation from the sawdust especially when it contacted minor wounds on the legs.
- Melilotus Mill.
The genus comprises about 20 species of fragrant herbs native to temperate and subtropical Eurasia, and northern Africa and Ethiopia (Mabberley 2008).
- Melilotus alba Medikus
- (syn. Melilotus officinalis Lam. ssp alba H. Ohashi & Y. Tateishi)
- White Sweet Clover, White Melilot
Sweet clover is grown as a green manure and hay crop. It contains coumarins which impart a distinctive odour. The coumarin precursors known as melilotosides, which are glucosides of 2-coumaric acid, can be converted by fungal action to dicoumarol if the plant is cut for hay under wet conditions. Dicoumarol (also known as dicumarol or melitoxin) was the first oral anticoagulant to be used in western medicine, but has now largely been replaced by warfarin (Reynolds 1996, Dewick 1997).
Dicoumarol formed in spoiled sweet clover may cause haemorrhagic sweet clover disease (also known as bleeding disease) in cattle and sheep, which may be fatal (Wignall et al. 1961). Cattle so affected develop subcutaneous haemorrhages and bleeding from the vagina and other orifices (Stahmann et al. 1941, Radostits et al. (1980), Yamini et al. 1995, Puschner et al. 1998). Humans may develop similar symptoms from dicoumarol use (Groth & Tengstrom 1960) or abuse (Hofstetter & Clement 1970).
In an investigation of 'weed dermatitis' the plant produced negative patch test reactions (Shelmire 1939).
- Melilotus indica All.
- (syns Trifolium melilotus L. var indica L., Sertula indica Kuntze, Melilotus parviflora Desf.)
- Sour Clover, Small-Flowered Melilot, Small Melilot
Wignall et al. (1961) described an investigation of haemorrhagic disease in cattle that had been fed poor quality hay containing a large proportion of Melilotus indica. The presenting symptom was epistaxis. The disorder could also be produced experimentally in rabbits. See also Melilotus alba Medikus above.
In NW Moroccan traditional medicine, the leaves and flowers are added to bathwater for the external treatment for warts, rheumatism, and wounds. Ocular infections are also treated (Merzouki et al. 2000).
- Melilotus officinalis Pallas
- (syns Melilotus officinalis Lam., Melilotus officinalis Medikus, Melilotus arvensis Wallroth, Sertula arvensis Kuntze, Trifolium melilotus L. var officinalis L.)
- Common Melilot, Ribbed Melilot, Yellow Sweet Clover, King's Clover
Referring to Melilotus arvensis, Stuart (1911) notes that, when ingested, the plant is said to have the property of imparting its fragrance to the body. He notes also that the mucoid sap found in the stalk and root is regarded in Chinese traditional medicine as an excellent local application for piles (haemorrhoids) and prolapse of the anus.
Hay made from this species, can cause haemorrhagic skin necrosis in animals if spoiled by fungal action (Wignall et al. (1961), Kingsbury 1964). See also Melilotus alba Medikus.
Dicoumarol has been implicated in alopecia (Cornbleet and Holt 1957).
- Melilotus suaveolens Ledeb.
A decoction of the plant is used in Indo-China as a lotion to treat eye diseases (Perry & Metzger 1980).
Two species are found in west equatorial Africa.
- Microberlinia spp.
The wood is said to be irritant (Zafiropoulo et al. 1968) but the name zebrawood is also applied to Astronium.
Several species notably Millettia ferruginea yield rotenone, the cutaneous effects of which are noted under Derris.
- Millettia laurentii
Splinters of wenge cause persistent inflammation and exposure to the sawdust can cause abdominal cramps.
This species can cause mucocutaneous reactions in wood-workers (Hublet et al. 1972, Oleffe et al. 1975a). Hausen (1974) was able to sensitise guinea pigs to ethanol/chloroform extracts of the wood.
- Millettia megasperma
- Native Wisteria
The exudation of the cut vine of this Australian species is very astringent from a high content of tannin and yields a kino (Maiden 1891).
- Millettia pinnata Panigrahi
- (syns Cajum pinnatum Kuntze, Cytisus pinnatus L., Derris indica Benn., Galedupa indica Lam., Pongamia glabra Vent., Pongamia pinnata Merr.)
- Honge Tree, Indian Beech, Karum Tree, Pongame Oiltree, Poonga Oil-Tree
[Information available but not yet included in database]
- Millettia stuhlmannii Taub.
- (syn. Lonchocarpus mossambicensis T. Sim)
- Mutsara, Panga Panga
This species has been implicated in asthma of wood-workers (Ordman 1949b).
Oleffe et al. (1975a) listed the wood of this species as a cause of dermatitis in the Belgian timber industry.
Perhaps 500 species are found in tropical and sub-tropical America, a few in Africa and Asia. They are frequently thorny.
The caterpillar of the flannel moth which haunts mimosa trees in the southern United States can cause contact dermatitis (Grater 1975). The common name mimosa can refer to Mimosa and to some species of Acacia.
- Mimosa pigra
- (syn. Mimosa asperata)
- Thorn of Blood
The roots are irritant (Irvine 1961).
- Mimosa pudica L.
- (syns Mimosa balansae Micheli, Mimosa hispidula Kunth)
- Sensitive Plant
This thorny plant is injurious to the gut of animals which eat it (Burkill 1935). Mimosine is derived from the plant; the effects of this chemical are noted under Leucaena.
Ten species are native to tropical South America and the West Indies.
- Mora excelsa
The wood-dust is acrid and irritant to the respiratory tract (Handbook of Hardwoods 1956, Orsler 1973). M. gonggrijpii appears to have a similar effect.
- Mora spp.
- Mora, Morabukea, Nato
The fine sawdust produces a bitter taste on the lips (Kukachka 1970).
120 species are found in tropical and sub-tropical regions. Some have stinging hairs on the pods.
- Mucuna spp.
The English name 'cowitch' came into being by attempts to force a meaning (i.e. itching) into a distorted form, first 'ke-whage' and then 'kowhage' of the Hindu name 'kewach' (Burkill 1935). Labourers in sugar-cane fields developed urticarial reactions from the plants (Behl et al. 1966). The hairs of the wild species of Mucuna sting when the plants themselves are long dead (Burkill 1935). Various authors report the following species as having irritant hairs: M. atropurpurea, M. coriacea, M. flagellipes, M. gigantea, M. hirsuta, M. melanocarpa, M. monosperma, M. nigricans, M. poggei, M. pruriens, M. quadrilata, M. sloanei, M. stans, and M. urens. The hairs of M. urens were noted to be airborne and capable of producing irritation at a distance (Allen 1943).
- Mucuna pruriens DC. var pruriens
- (syns Dolichos pruriens L., Mucuna prurita Wight, Stizolobium pruriens Medikus)
- Buffalo Bean, Pica-Pica, Cowhage, Cowitch, Velvet Bean, Hell Fire Bean, Itchy Bean
The velvety surface of the crooked pods is made up of thousands of rigid, brittle barbed hairs which are easily detached on contact with the skin. Penetration of the skin by the hairs produces itching and irritation that may last for some time. (Allen 1943). Dahlgren & Standley (1944) note that the bristles separate easily from the pods and may be carried in the wind. They caution that if the hairs lodge in the eyes they may cause serious trouble.
Labourers were observed to develop urticaria; some developed conjunctivitis and keratitis. Dried hairs mixed in the soil can irritate the feet (Dao 1967).
Cowhage hairs were formerly used in an ointment, Ung. Urticans (White 1887). The stinging hairs have been used in Africa to simulate leprosy, being first applied to the skin which is then rubbed with the latex of a Euphorbia. This causes swelling and numbness, persistent for several weeks (Dalziel 1937).
The active pruritogenic principle is a proteolytic enzyme, mucunain (Arthur and Shelley 1955, Shelley and Arthur 1955a, Shelley and Arthur 1955b).
30 species are native to Madagascar, one to tropical Africa, southern India and Ceylon.
- Mundulea sericea
This species yields rotenone (Irvine 1961), the cutaneous effects of which are noted under Derris.
- Myrocarpus Allemão
Five species are to be found in tropical South America (Mabberley 2008). They provide timber (afrormosia Rio, cabreuva, santos mahogany, incienso) that is used commercially for parquet flooring, and yield an aromatic balsam ("cabreuva balsam") resembling balsam of Peru.
- Myrocarpus fastigiatus Allemão
- Brazilian Myrocarpus, Cabreúva
Arctander (1960) and Opdyke & Letizia (1982) record that this species is a source of a perfumery material known as cabreuva oil, the main constituent of which is d-nerolidol (see also Myrocarpus frondosus below). The oil is also known as Myrocarpus fastigiatus wood oil.
- Myrocarpus frondosus Allemão
- (syn. Leptolobium punctatum Benth.)
- Brazilian Myrocarpus, Cabreúva, Incienso, Common Sassafras
An essential oil, known as cabreuva oil or as Myrocarpus frondosus wood oil, is obtained by steam distillation of the wood chips. It provides nerolidol and hence the sesquiterpene alcohol farnesol. Man himself uses farnesol, which occurs in his own surface lipid, as a perfume (Nicolaides 1965).
According to Opdyke & Letizia (1982), undiluted cabreuva oil was neither irritating nor phototoxic when applied to the backs of hairless mice or swine. When tested at a concentration of 6% in petrolatum, it was non-irritant and non-sensitising in 25 human volunteers.
Di Stasi et al. (2002) record that a macerate in water prepared from this species is popularly used in the Brazilian tropical Atlantic forest for its anti-inflammatory and wound healing properties.