Common Name: Asthma Weed

General Information

Euphorbia hirta is a densely hairy, prostrate to ascending, little-branched annual plant with one to several stems arising from a central tap-root; it can grow 15 - 50cm tall and wide[, ].
The plant is harvested from the wild for use as a medicine. An important medicinal herb, it is often sold in local markets and through the internet[].
Euphorbia hirta is a short-lived weed that germinates and flowers throughout the year and can fruit in less than a month. It has become a very common weed of the tropics and subtropics[].

Known Hazards

The sap contains a latex which is toxic on ingestion and highly irritant externally, causing photosensitive skin reactions and severe inflammation, especially on contact with eyes or open cuts. The toxicity can remain high even in dried plant material[]. Prolonged and regular contact with the sap is inadvisable because of its carcinogenic nature[].

Botanical References

,

Range

A pantropical plant, probably originating in tropical America and possibly native from S. America to southern USA.

Habitat

Waste places and cultivated fields in lowland Japan[]. Moist open places at elevations up to 1,800 metres in Nepal[]. Cultivated fields, gardens, roadsides and waste places, from sea-level up to 2,000 metres[].

Properties

Weed Potential	Yes
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Annual
Height	0.30 m
Pollinators	Insects
Cultivation Status	Wild

Cultivation Details

Euphorbia hirta is a widespread plant that is found native or naturalized throughout tropical and subtropical regions of the world. It is not frost tolerant, but can be grown as an annual in temperate regions with warm to hot summers.
Prefers a light well-drained moderately rich loam in an open sunny position[].
Hybridizes with other members of this genus[].
The ripe seed is released explosively from the seed capsules[].
Members of this genus are rarely if ever troubled by browsing deer or rabbits[].
This genus has been singled out as a potential source of latex (for making rubber) for the temperate zone, although no individual species has been singled out[].
Euphorbia hirta is a host to many fungal pathogens and may as such act as a reservoir of pathogenic fungi, which can infect nearby susceptible crops. Trypanosomatid flagellates (Phytomonas spp.) were detected in Euphorbia hirta plants in coconut plantations. Euphorbia hirta also acts as a host to several insect vectors, including the aphid Aphis craccivora, a vector of the rosette virus disease of groundnut, and Aphis gossypii[].

Edible Uses

Tender young leaves and shoots - cooked as a vegetable[, ]. A famine food, used when all else fails[, ] and I would have to be very desperate to eat it even then[]. The leaves can cause intestinal complaints[].

Medicinal

Asthma weed is a very important herbal medicine both within its native range and also beyond[]. It has traditionally been used to treat respiratory system disorders including bronchitis, asthma, hay fever, emphysema, coughs, colds and laryngeal spasm, though in modern herbalism it is more used in the treatment of gastrointestinal disorders, including intestinal parasites, diarrhoea, peptic ulcers, heartburn, vomiting and amoebic dysentery[, ]. The plant is also used as a diuretic to treat uro-genital diseases, such as kidney stones, menstrual problems, sterility and venereal diseases[]. The plant has a reputation as an analgesic to treat severe headache, toothache, rheumatism, colic and pains during pregnancy. It is used as an antidote and pain relief of scorpion stings and snakebites[]. It should not be used without expert guidance, however, since large doses cause gastro-intestinal irritation, nausea and vomiting[].
Externally, the plant is also used to treat affections of the skin and mucous membranes, including warts, scabies, ringworm, thrush, aphthae, fungal afflictions, measles, Guinea-worm and as an antiseptic to treat wounds, sores and conjunctivitis[].
The plant is anodyne, antiinflammatory, antipruritic, carminative, depurative, diuretic, febrifuge, galactagogue, purgative and vermifuge[, ].The aerial parts of the plant are harvested when in flower during the summer and can be dried for later use[].

The stem, taken internally, is famed as a treatment for asthma, bronchitis and various other lung complaints[, , ]. The herb relaxes the bronchioles but apparently depresses the heart and general respiration[]. It is usually used in combination with other anti-asthma herbs such as Grindelia camporum and Lobelia inflata[]. It is also used to treat intestinal amoebic dysentery[].
The leaves are mixed with those of Datura metel in preparing 'asthma cigarettes'[].

The whole plant is decocted and used in the treatment of athlete's foot, dysentery, enteritis and skin conditions[]. It has been used in the treatment of syphilis[].

The sap (latex) is applied to warts in order to destroy them[, ]. The treatment needs to be repeated 2 - 3 times a day over a period of several weeks to be fully effective[]. The sap is also used to treat fungal infections between the toes[].
The latex is used to facilitate removal of thorns from the skin[].

The aerial parts of the plant contain several medically active constituents including various terpenoids[].
The aerial parts and roots also contain diterpene esters of the phorbol type and ingenol type, tannins, acids such as ellagic acid, gallic acid, tannic acid, maleic acid and tartaric acid[]. Various flavonoids have also been isolated[].
The stems contain the hydrocarbon hentriacontane and myricyl alcohol.
The latex contains inositol, taraxerol, friedelin, β-sitosterol, ellagic acid, kaempferol, quercitol and quercitrin.
Several of the traditional medicinal uses have been supported by research. An aqueous extract of the whole plant acts as an antidiarrhoeal agent by anti-amoebic, antibacterial and antispasmodic activities. The antidiarrhoeal activity is attributed to quercitrin[]
A crude plant extract and an ethanolic extract had significant anti-amoebic activity against Entamoeba histolytica in vitro at 35 mg/ml. An aqueous lyophilysate of the whole plant showed higher activity against Entamoeba histolytica than either the ethyl acetate or methanol extracts, at 30 mg/ml[].
An aqueous plant extract showed concentration-related activity against non-pathogenic amoebae of the Amoeba proteus type[].
Different extracts from the aerial parts showed antibacterial activity against a wide spectrum of both gram-positive and gram-negative bacteria. Extracts of the aerial parts showed strong antibacterial activity against Shigella dysenteriae, a causal agent for dysentery in humans[]. The active compound was found to be ethyl gallate, which has broad spectrum antibiotic activity at non-toxic doses[].
A crude ethanol extract of the whole plant showed dose-dependent activity against Candida albicans, but not against several other pathogenic fungi[]
Ethanol, petroleum ether and dichloromethane extracts of whole plants showed significant antiplasmodial activity and decreased growth of Plasmodium falciparum by 89 - 100% at a test concentration of 6 μg/ml[].
Water and ethanolic leaf extracts produced a time-dependent increase in urine output[]. A methanol extract of leaves and stems inhibited the activity of angiotensin-converting enzyme by 90% at 500 μg and 50% at 160 μg. The extract (10 mg/100 g, intraperitoneally) significantly decreased the amount of water consumed[].
An ethanolic extract of the whole plant showed a dose-dependent ulcer protective effect[]. The active compound was found to be quercetin, which had an anti-ulcer activity ranging from 48 - 64% comparable to 61 - 80% of the standard drug ranitidine[].
An ethanolic extract of the aerial parts showed significant hepatoprotective activity[].
Extracts of whole plant material have oestrogenic activity[]

Other Uses

Several of the extracts of Euphorbia hirta showed potential for controlling plant diseases and pests. For example, a whole plant extract inhibited growth of vascular wilt (Fusarium oxysporum) and the causal agent of sheath rot of rice, Sarocladium oryzae; aqueous extracts of the aerial parts inhibited aflatoxin production by Aspergillus parasiticus on agricultural crops, including rice, wheat, maize and groundnuts[]. Leaf extracts completely inhibited soft rot infection caused by the bacteria Erwinia carotovora. The infectivity of tobacco mosaic virus on Nicotiana glutinosa was strongly inhibited (>80%) by tannins extracted from the aerial parts[]. The latex inhibited sugarcane mosaic virus-A by 78.5% and sugarcane mosaic virus-F by 80%[].
Root and leaf extracts showed nematicidal activity against Meloidogyne incognita; a whole plant extract effectively reduced hatching in the nematode Heterodera avenae. A 10% ethanol crude extract showed significant larvicidal action against the larvae of the tick Boophilus microplus[].

Propagation

Seed - sow mid to late spring in situ. Germination usually takes place within 2 - 3 weeks at 20°c.
It might be best to sow the seed in a cool greenhouse in early early spring. When they are large enough to handle, prick the seedlings out into individual pots and plant out the seedlings in late May. This will give the plants longer to grow and mature.