LAUSR

In the present study, the surface ornamentations of both megaspores and microspores of 20 species of Selaginella were studied using scanning electron microscopy. The results of the present study showed that the megaspore surface ornamentations are complementary to the corresponding microspore surface ornamentations. In detail, reticulate surface ornamentation of megaspores is complementary to granulate and baculate ornamentations of microspores; verrucate ornamentation of megaspores is complementary to scabrate ornamentation of microspores; granulate ornamentation of megaspores is complementary to verrucate–rugulate or verrucate ornamentations of microspores; verrucate–rugulate ornamentation of megaspores is complementary to spinulate, verrucate, or verrucate–rugulate ornamentations of microspores; tuberculate ornamentation of megaspores is complementary to lamellate, tuberculate or verrucate ornamentations of microspores. Complementary ornamentation between megaspores and microspores allows microspores to adhere to megaspores. Our observations support the “synaptospory” hypothesis, that is, spore surface ornamentation plays a part in keeping or bringing spores together during their dispersal in the pteridophytes.