However, his seven types are characterized mainly by features such as the number of integuments and seed coat layers, the vascular supply of the ingrowths, and the preformation of the rumination in tissues of the seed coat.
* structure and extent of rumination (number, size, origin, distribution, regularity, and shape of ingrowths)
* correlation between the positions of vascular bundles and ingrowths
* presence or absence of vascular supply of ingrowths
First, the fact that the ingrowths often contain phenolic substances or ethereal oils led to the assumption that rumination might make the seeds less attractive to predators (Muller, 1887; Osenbrug, 1894; Goebel, 1933).