Pollen and Pollination in Ephedra (gnetales)
نویسندگان
چکیده
منابع مشابه
Moonlight pollination in the gymnosperm Ephedra (Gnetales).
Most gymnosperms are wind-pollinated, but some are insect-pollinated, and in Ephedra (Gnetales), both wind pollination and insect pollination occur. Little is, however, known about mechanisms and evolution of pollination syndromes in gymnosperms. Based on four seasons of field studies, we show an unexpected correlation between pollination and the phases of the moon in one of our studied species...
متن کاملFormer diversity of Ephedra (Gnetales): evidence from Early Cretaceous seeds from Portugal and North America.
BACKGROUND AND AIMS The extant species of the seed plant group Gnetales (Ephedra, Gnetum and Welwitschia) have been considered a remnant of a much greater, now extinct, diversity due to the pronounced differences in form and ecology among the genera. Until recently, this hypothesis has not been supported by evidence from the fossil record. This paper adds to the expanding information on Gnetale...
متن کاملDevelopment of sterile ovules on bisexual cones of Gnetum gnemon (Gnetaceae).
Angiosperms and Gnetales (Ephedra, Gnetum, Welwitschia) represent the only seed plants that regularly produce bisexual cones. Unfortunately, the fertility and function of ovules formed on bisexual cones of Gnetales have remained unclear. Some reports indicate that the ovules are sterile while others indicate that they may develop into seeds. This study demonstrates three different developmental...
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Low seed yield is a limiting factor for cross breeding and hybrid seed production in cyclamen. This study was performed to investigate pollen germination and its relation to cross-pollination success and fruit set in this plant. In order to achieve a high level of pollen germination, the effect of different concentrations of chemical compounds were examined on in vitro pollen germination of cyc...
متن کاملPhylogenetic Relationships in Ephedra (Gnetales): Evidence from Nuclear and Chloroplast DNA Sequence Data
Sequences from the nuclear ribosomal internal transcribed spacer region 1 (nrDNA ITS1) and the plastid rps4 gene from the genus Ephedra (Ephedraceae, Gnetales) were obtained in order to infer phylogenetic relationships, character evolution, and historical biogeography in the genus. Within Ephedra the length of the nrDNA ITS1 varied from 1,081 to 1,143 basepairs (bp), in contrast to dramatically...
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