Isoetes Megaspore Surface Morphology: Nomenclature, Variation, and Systematic Importance

Development of megaspores and microspores inIsoetes japonicaA. Br. (Lycopodiophyta: Isoetaceae)

“…Given the considerable diversity of perispore patterns found in different species of Isoetes (Pfeiffer, 1922;Hickey, 1986), one important focus of future investigation should be to compare megaspore tetrads of different species. It would be interesting to determine whether the precise morphology of the perispore is established in the tetrad stage and simply elaborated upon when the tapetum disintegrates, as it appears to be in I. japonica, or not.…”

“…In particular, we were interested in studying differences in development between the monolete microspores and trilete megaspores. Megaspore characters have been strongly emphasised in the sectional and specific classification of the genus since Pfeiffer (1922) produced the first monographic treatment of Isoetes [for a more recent discussion, see Hickey (1986)]. As Blackmore and Crane (1998) reported, there is a direct correlation between the occurrence of proximal trilete apertures and simultaneous cytokinesis in pteridophytes.…”

Isoetes naipiana(Isoetaceae), a new species from southern Brazil

“…Spore size descriptions include the variation and the arithmetic average of 25 measurements, the first value corresponding to the polar axis and the second to the equatorial axis. The terminology used to classify the spore surface follows that of Hickey (1986) and Tryon & Lugardon (1990). Diagnosis -The general morphology of the plants differs markedly from the other species occurring in the region by the small size of the microphylls (up to 2.2 cm long) in mature plants, while at least twice as long in the remaining species.…”

“…2003). For South America, Fuchs-Eckert (1986) listed 75 species, while Hickey (1986) suggested 47. The diversity in Brazil is still far from being known in appropriate detail, due to poor collecting, difficulties in the preservation of samples, lack of fixed material for morphological and anatomical analysis, samples restricted to type material for many species, apparently narrow distributions, lack of easily observable characters, hybridization and polyploidy.…”

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

“…In this analysis, a description of the adapted Isoetes sehnemii spores of Fuchs-Eckert 342 CECILIA MACLUF, MARTA MORBELLI and GABRIELA GIUDICE (1986) is included. The joint study of microspores and megaspores in taxa of Isoetes with electronic microscopy has only been carried out for Isoetes savatieri Franchet by Morbelli (1980), Hickey (1985Hickey ( , 1986, Hickey et al (2003) and Macluf et al (2003b). The spores of other species of Isoetes were examined with TEM by Lugardon (1973Lugardon ( , 1986, Robert et al (1973), Prada Moral and Saenz de Rivas (1978), Tryon and Lugardon (1991), Taylor (1992Taylor ( , 1993 and Uehara et al (1991).…”