History in Africa carried an article in 1992 entitled “The European Introduction of Crops into West Africa in Precolonial Times.” I wrote this to correct an impression left by several historians that only maize and cassava were worth mentioning. My reading of precolonial African history had made it very clear that a great many new crops were brought to the continent during the slave-trade period. My initial geographical focus was what used to be called Lower Guinea, roughly the coast from Cape Palmas to Mt. Cameroon, but inevitably my research took in all of western Africa from Senegal to Angola and up to the southern fringe of the Sahara. My findings were admittedly interim, a sort of database for future refinement. And yet I was able to identify 86 introduced crops.

It was ingenuous of me to expect that one paper would suffice to over-turn what had become conventional wisdom. In 1995 John Iliffe, in 1997 Elizabeth Isichei, in 1998 John Reader repeated the maize-cassava mantra. In 2002 Christopher Ehret expanded the duo of exotic crops to include tobacco, peanuts, New World beans, Asian rice and sugar cane. David W. Phillipson reiterated in 2005 what he had said 20 years earlier, citing only maize, cassava and bananas. And in 2006 James L.A. Webb Jr. named just four: maize, cassava, peanuts and potatoes.

This pattern of minimization may reflect what seems to be a general disinclination of historians to dig deeply into botany. An important recent book titled Writing African History devotes only 17 of 510 pages to the subject.