There are seeds that, when cut in any plane, show a labyrinth structure (van Heel, 1970). This may be due to folding of the cotyledons (Burseraceae, Dipterocarpaceae), or to the presence of testa tissue within the seed. In the latter case the testa tissue may either be located in the endosperm only (‘ruminated seeds’ in Palmae, Annonaceae, etc.), or the testa tissue may interfere with the cotyledons. It is possible that in some cases the testa at first interferes with the endosperm, and later on, when the embryo has become larger, also interferes with the cotyledons (Corner, 1966, in some Palmae). In the case of testa tissue interfering with the cotyledons, there are probably two possibilities. Firstly the testa may be located between portions of folded and lobed, mostly flat, cotyledons — sometimes surrounded by a small amount of endosperm — (Kingiodendron, Erycibe, Argyreia, Neokeithia). Secondly the testa can be located in many crevices in massive cotyledons (Hernandia, Mangifera). However, it seems that a distinction among labyrinth-seeds will be rather arbitrary, as long as the precise ways of development remain unknown. It is very probable that different ontogenies may yield much resembling end-stages (Corner, 1966; van Heel, 1971; Periasamy 1962).