Morphology and ultrastructure of megaspores and microspores of Isoetes sehnemii Fuchs (Lycophyta)

Anais da Academia Brasileira de Ciências

Cecilia Macluf¹  Marta Morbelli¹  Gabriela Giudice¹ 

[1] ,Facultad de Ciencias Naturales y Museo de La PlataBuenos Aires,Argentina

关键词: Lycophyta;    Isoetes;    Brazil;    spores;    ultrastructure;    sculpture;    Palynology;    Lycophyta;    Isoetes;    Brasil;    esporos;    ultraestrutura;    escultura;    Palinologia;   

DOI  :  10.1590/S0001-37652010000200010

来源: SciELO

【 摘 要 】

The morphology and wall ultrastructure of megaspores and microspores of Isoetes sehnemii that grows in Brazil were analyzed as part of the study of the Isoetaceae present in Southern South America. The observations were performed with light, scanning and transmission electron microscopes. The megaspores are trilete, 350-450μm in equatorial diameter. The surface is reticulate. In section, the sporoderm is 100μm thick including the ornamentation. The wall is composed of a siliceous perispore, which consists of short fused flatten, elements forming a three-dimensional mesh. The exospore has two zones of different structure. The endospore is fibrillar. The microspores are monolete, 21-27μm in equatorial diameter. The sporoderm is composed of a sporopollinic rugulate perispore. A space between the paraexospore and the exospore is evident. The exospore is compact. The endospore is fibrillar. The ultrastructural analysis akes hoologies evident concerning structure and organization of the layers belo the perispore in both spore types. A possible similarity and stability in the ultrustructure of the present spores and fossils could be also inferred. In addition, there would be a correlation among the plant habitat, the spore ornamentation and the geographic distribution.

【 授权许可】

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