Euphorbia tirucalli

Euphorbia tirucalli, Photo: Michael Lahanas

Classification System: APG IV

Superregnum: Eukaryota
Regnum: Plantae
Cladus: Angiosperms
Cladus: Eudicots
Cladus: Core eudicots
Cladus: Rosids
Cladus: Eurosids I
Ordo: Malpighiales

Familia: Euphorbiaceae
Subfamilia: Euphorbioideae
Tribus: Euphorbieae
Subtribus: Euphorbiinae
Genus: Euphorbia
Subgenus: E. subg. Euphorbia
Sectio: E. sect. Tirucalli
Species: Euphorbia tirucalli
Name

Euphorbia tirucalli L., 1753
Synonyms

Homotypic
Tirucalia indica Raf., Fl. Tellur. 4: 112 (1838).
Arthrothamnus tirucalli (L.) Klotzsch & Garcke, Monatsber. Königl. Preuss. Akad. Wiss. Berlin 1859: 251 (1859).
Tirucalia tirucalli (L.) P.V.Heath, Calyx 5: 93 (1996).
Heterotypic
Euphorbia viminalis Mill., Gard. Dict. ed. 8: n.º 15 (1768), nom. illeg.
Euphorbia rhipsaloides Lem., Ill. Hort. 4(Misc.): 72 (1857).
Euphorbia laro Drake, Bull. Mus. Hist. Nat. (Paris) 5: 307 (1899).
Euphorbia geayi Costantin & Gallaud, Bull. Mus. Hist. Nat. (Paris) 11: 347 (1905).
Euphorbia media N.E.Br. in D.Oliver & auct. suc. (eds.), Fl. Trop. Afr. 6(1): 556 (1911).
Euphorbia media var. bagshawei N.E.Br. in D.Oliver & auct. suc. (eds.), Fl. Trop. Afr. 6(1): 556 (1911).
Euphorbia scoparia N.E.Br. in D.Oliver & auct. suc. (eds.), Fl. Trop. Afr. 6(1): 557 (1911).
Euphorbia tirucalli var. rhipsaloides (Willd.) A.Chev., Rev. Bot. Appl. Agric. Trop. 13: 547 (1933).
Euphorbia suareziana Croizat, Natl. Hort. Mag. 1934(Jan.): 99 (1934).

Distribution
Native distribution areas:

Continental: Africa
Angola; Botswana; Burundi; Cape Provinces; Botswana; Burundi; Cape Provinces; Bangladesh; Eritrea; Ethiopia; Ghana; Kenya; KwaZulu-Natal; Madagascar; Malawi; Mozambique; Nigeria; Rwanda; Senegal; Somalia; Sudan; Swaziland; Tanzania; Thailand;
Continental: Asie
Assam; India

References: Brummitt, R.K. 2001. TDWG – World Geographical Scheme for Recording Plant Distributions, 2nd Edition
References
Primary references

Linnaeus, C. 1753. Species plantarum, exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas. Tomus I. Pp. [I–XII], 1–560. Impensis Laurentii Salvii, Holmiae [Stockholm]. BHL Reference page. : 452.

Links

Govaerts, R. et al. 2020. Euphorbia tirucalli in World Checklist of Selected Plant Families. The Board of Trustees of the Royal Botanic Gardens, Kew. Published online. Accessed: 2020 Jul 12. Reference page.
International Plant Names Index. 2020. Euphorbia tirucalli. Published online. Accessed: Jul 12 2020.
Govaerts, R. et al. 2020. Euphorbia tirucalli in Kew Science Plants of the World online. The Board of Trustees of the Royal Botanic Gardens, Kew. Published online. Accessed: 2020 Jul 12. Reference page.
Tropicos.org 2020. Euphorbia tirucalli. Missouri Botanical Garden. Published online. Accessed: 12 Jul 2020.
USDA, ARS, Germplasm Resources Information Network. Euphorbia tirucalli in the Germplasm Resources Information Network (GRIN), U.S. Department of Agriculture Agricultural Research Service. Accessed: 08-Apr-12.

Vernacular names
Afrikaans: Kraalnaboom
English: Pencil tree, Rubber euphorbia, Indian tree spurge
español: Aveloz, Consuelda
suomi: Mehipuutyräkki, pensastyräkki
français: Euphorbe antivenerien
português: Almeidinha
සිංහල: නවහන්දි
中文: 绿玉树

Euphorbia tirucalli (commonly known as Indian tree spurge, naked lady, pencil tree, pencil cactus, fire stick, or milk bush[2]) is a tree that grows in semi-arid tropical climates. A hydrocarbon plant, it produces a poisonous latex that can cause temporary blindness.[3]

Description
Flower closeup

The pencil tree is a shrub or small tree with pencil-thick, green, smooth, succulent branches that reaches heights of growth of up to 7 meters. It has a cylindrical and fleshy stem with fragile succulent twigs that are 7 mm thick, often produced in whorls, longitudinally, finely striated. The oval leaves are 1 to 2.5 cm long and about 3 to 4 mm wide; they usually fall off early. It contains a milky, toxic and corrosive sap. The yellow flowers are at the ends of the branches.[4]
Habitat

It has a wide distribution in Africa in black clay soils, being prominently present in northeastern, central and southern Africa. It may also be native in other parts of the continent as well as some surrounding islands and the Arabian peninsula and has been introduced to many other tropical regions, such as Brazil, India, Vietnam, the Philippines and Ghana. It grows in dry areas, especially the savanna, and is often used to feed cattle or as hedging.[1] It is well known in Sri Lanka where it is called Kalli in Tamil, as mentioned in the Akananuru by the Sri Lankan Tamil poet Eelattu Poothanthevanar and in Sinhala: වැරදි නවහන්දි, ගස් නවහන්දි Weradi Navahandi or Gass Nawahandi.[5]
Toxicology

The milky latex from E. tirucalli is extremely irritating to the skin and mucosa and is toxic.[6] Exposure to it can cause temporary blindness. Skin contact causes severe irritation, redness and a burning sensation. If ingested, it can cause burns to the mouth, lips and tongue. It is suggested to wear eye protection gear and gloves for handling the plant.
Traditional medicine

Euphorbia tirucalli is used as alternative medicine in many cultures. Attempts have been made to use it to treat cancer, excrescence, tumors, warts, asthma, cough, earache, neuralgia, rheumatism, and toothaches in countries including Brazil, India, Indonesia, and Malaysia.[7][8]

Euphorbia tirucalli has been promoted as an anticancer agent, but research shows that it suppresses the immune system, promotes tumor growth, and leads to the development of certain types of cancer.[6] Euphorbia tirucalli has also been associated with Burkitt's lymphoma and is thought to be a cofactor of the disease rather than a treatment.[9]
Uses

Its latex can also be used as fuel. This led chemist Melvin Calvin to propose the exploitation of E. tirucalli for producing oil. This usage is particularly appealing because of the ability of E. tirucalli to grow on land that is not suitable for most other crops. Calvin estimated that 10 to 50 barrels of oil per acre was achievable. In the 1980s the Brazilian national petroleum company Petrobras began experiments based on these ideas. It has also been used in the production of rubber, but neither have been very successful.[1]