Spore morphology and wall ultrastructure of Lomariocycas (Blechnaceae) species from America.

The spores of 11 species of Lomariocycas that grow in America were studied: Lomariocycas aurata , L. columbiensis , L. cycadifolia , L. insularis , L. magellanica , L. moritziana , L. rufa, L. schomburgkii, L. shaferi , L. underwoodiana and L. werckleana. The study was performed with light microscope (LM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The spores are monolete of 61–100 μm in equatorial diameter and 40–79 μm in polar diameter. The exospore is 1.5–4.8 μm thick and in section is two-layered. The perispore is folded, two types of folds were observed in the different species analyzed and also they could be fused in different ways. In section, it is 0.5–13.8 μm thick and is two-layered. The outer layer is single stratified and the inner layer is three-stratified. The spores of some species are illustrated and described for the first time. Moreover, the sporoderm ultrastructure of L. underwodiana was not studied until now. The differences found in perispore morphology and ultrastructure could be valuable characters for systematic and phylogenetic purposes. • The spores of Lomariocycas from America are folded. • Two types of folds are defined: (1) narrow and high, (2) wide and robust. • The two types of folds could be partially or totally fused. • The spores of some species are illustrated and described for the first time. • In the species analyzed the sporoderm ultrastructure is similar. [ABSTRACT FROM AUTHOR]