Figure 1. Fruit forms of the African oil palm Elaeis guineensis.

a, Dura (Sh/Sh) fruit forms have a thick lignified shell surrounding the kernel, which is absent in pisifera (sh/sh). F1 hybrid palms (Sh/sh) have an intermediate fruit form (tenera) which is much higher yielding than either parent in terms of mesocarp oil. b, Dura, tenera and pisifera fruit stained for lignin (red) with phloroglucinol.