In the protologue Baker states that S. masukuense is intermediate between S. guineense (“owariense”) and S. cordatum. It is possible that S. masukuense originated by hybridization between S. cordatum and S. guineense subsp. afromontanum. This hypothesis is supported by the fact that S. masukuense subsp. masukense only occurs where the ranges of these two taxa overlap, and most collectors state that it is rare or occurs as isolated individuals. Present evidence, however, is inconclusive since iS. masukuense is by no means exactly intermediate between its putative parents and is not known to be connected to S. cordatum by other intermediates. This is in contrast to S. cordatum and S. guineense subsp. guineense which are more-or-less completely connected by a chain of intermediates (see p. 194). Other considerations weigh against the supposed hybrid origin of S. masukuense. S. masukuense subsp. pachyphyllum only differs from the nominate subsp. in having smaller, sometimes proportionately broader, less acuminate leaves and the dividing line between them is somewhat arbitrary. It occurs at higher altitudes than S. cordatum in the F.Z. area. Its fruit shows none of the features of that of S. cordatum. Unfortunately the fruit of subsp. masukuense is still unknown. The possibility that S. masukuense subsp. pachyphyllum may have originated by hybridization between S. masukuense and small leaved variants (Group B) of S. guineense subsp. afromontanum cannot be ruled out.