Anatomical structure of seed coat in Pombalia big gibbosa and P. calceolariar from Argentina (Violaceae)

In this study, the anatomical structure of seed-coat of Pombalia bigibbosa (A. St.-Hil.) Paula-Souza and P. calceolaria (L.) PaulaSouza from Argentina was studied for the first time in the Violaceae. The anatomy of seed-coat revealed the presence of three layers in testa derived from outer integument in both species however the presence of layers in tegmen was different between the analyzed species, P. bigibbosa presented two layers meanwhile P. calceolaria exhibited three layers derived from the inner integument in the mature seed-coat. The presence of a conspicuous elaiosome with oily drops was observed in both species, this structure had been observed in the genus Viola and it would be related with the attraction and dispersion mediated by ants in these species of the genus Pombalia in nature. In this sense, the myrmecochory in these violets species explains the multiple evolutionary origins in the angiosperm plants and is proposed like an example of convergent evolution