A number of scientists have attempted to define the origin of physic nut, but the source remains controversial.
Martin and Mayeux (1984) identified the Ceara state in Brazil as a centre of origin but without giving any arguments. Dehgan and Webster (1979) cite Wilbur(1954) as follows:
“it was without doubt part of the flora of Mexico and probably of northern Central America before the arrival of Cortez, and it most likely originated there … the subsection, hence, appears to be one which originally was nearly or completely restricted to Mexico.”
According to other sources, the physic nut seems to be native to Central America as well as to Mexico where it occurs naturally in the forests of coastal regions( Aponte 1978). However, Dehgan (pers. comm.) did not find true wild physic nut plants when collecting Jatropha’s in Mexico. Those he found had always “escaped” from cultivated hedges. During a visit to Professor Dehgan’s Horticultural Systematics Laboratory, the author checked hundreds of herbarium specimens from the following herbaria for the distribution of the physic nut in Mexico, Central America and the Caribbean: DAV, F,FLAS, GH, MICH, MO, NY, RSA, TEX, UC and US. The material collected originated mostly from Mexico and all Central American countries: Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua and Panama, with the majority coming from Mexico. Many records also exist for the Caribbean: Bahamas, Cuba, Dominica, Dominican Republic, Haiti, Puerto Rico, Saint Lucia, Santo Domingo, St. Croix, Trinidad and other West Indian countries. In the following South American countries, the physic nut occurs to a lesser extent, according to their representation in the herbaria listed above: Argentina, Bolivia, Brazil, Colombia, Ecuador and the Galapagos Islands, Paraguay, Peru and Venezuela. It has been introduced into Florida. Herbarium specimens of the Americas were usually collected from hedges along roads and paths, live fence posts or disturbed sites (“disturbed forest”). Standley and Steyermark (1949) confirm this and state for Guatemala that “the shrub may not be native in Guatemala, since it is found principally in hedges, but if not, doubtless it has been in cultivation for a long time”.
However, the information provided by many collectors seems to support the argument that the species was collected from “natural” vegetation in the Americas, as the following vegetation forms were given on the herbarium labels mentioned above: bosque humido, forest, bosque seco tropical, cactus and thorn scrub, shrubby slope, thicket near river bank, tropical dry forest, bosque seco y espinoso, dry steep hillside, woodland, hillside with dense shrubs and woods, or coastal thickets. It is highly probable that the centre of origin of the physic nut is in Mexico (and Central America) since it is not found in these forms of vegetation in Africa and Asia but only in cultivated form. The “true” centre of origin, however, still has to be found. To elucidate this, the original collecting sites in Mexico and Central America would have to be revisited and the existing diversity assessed, preferably by molecular techniques.
From the Caribbean, this species was probably distributed by Portuguese seafarers via the Cape Verde Islands and former Portuguese Guinea (now Guinea Bissau) to other countries in Africa and Asia. No facts are available in the literature before 1800 as to when the physic nut was introduced into Cape Verde (Serra 1950). Freitas (1906), citing Pusich, says that the physic nut was already known several years prior to 1810, as he mentioned it in his book “Memoria ou descripção physico-politica das ilhas de Cabo Verde”. Chelmicki and Varnhagen (1841) mention that exports of physic nuts had al-ready begun in 1836. Many decrees were published in the “Boletim Oficial de Cabo Verde” from 1843 onwards to promote the planting of physic nut (Freitas 1906; Serra1950).Burkill (1966) assumes that the Portuguese brought the physic nut to Asia: “Perhaps it did not reach Malacca until a date when the Dutch were in possession, for the Malays call it by a name meaning Dutch castor oil. Nevertheless, the Portuguese transported it to the Old World. The Javanese, among other names, call it Chinese castor oil. It is regarded in most countries, in Africa as well as in the East, as the ‘castor oil plant’, which shows that it was brought in and planted for the oil; further, it is widely known as the ‘hedge castor oil plant’, showing where it was planted, namely in hedges. Merrill (Bur. Gov. Lab. Philipp. 6, 1903 p. 27) shows that it was in the Philippines before 1750.” Today it is cultivated in many countries.