Appan, 1973;Nassar, 1978; Hersey, 1983;Bai et al., 1993). The plants contain lactifers and produce latex, andM. glaziovii is used as a minor source ofrubber (Cock, 1985). Cassava is native to tropical South America, and is one of the oldest cultivated crops (Jennings, 1976) with possibly two centres of origin. Since cassava does not exist in the wild state, and its wild progenitors are not known, the regions of its domestication are disputed (Renvoize, 1972;Rogers and Appan, 1973;Rogers and Flemming, 1973;Nassar, 1978