For the samples evaluated here, their seed viability, as determined by the ability to reduce TTC to the red coloured formazon (Lauzer et al., 1994; Rasmussen, 1995), was found to below for D. bigibbum var. compactum at 32.6% viability. In somesupport of this low seed viability is that most of the seeds wereclearly morphologically deformed with abortive and incompletelydeveloped embryos (Fig. 2C). In contrast, seeds from D. formosumwere found to be highly viable, with 94.1% viability, as determinedby positive formazon staining, and morphologically most seeds appeared normal with fully mature embryos