Sökning: "Gnetales"

Hittade 5 avhandlingar innehållade ordet Gnetales.

  1. 1. The Gnetales: fossils and phylogenies

    Författare :Catarina Rydin; Else Marie Friis; Mari Källersjö; Ulf Swensson; Susana Magallón; Stockholms universitet; []
    Nyckelord :seed plants; Gnetales; Ephedra; fossils; DNA; phylogeny; morphology;

    Sammanfattning : The phylogeny of seed plants has been debated for more than a hundred years and is still not fully understood. Morphological analyses have consistently resulted in a phylogeny in which cycads are the earliest diverging seed plants, and Gnetales and angiosperms are sisters. Molecular data has, however, rarely supported this result. LÄS MER

  3. 2. Pollination in Ephedra (Gnetales)

    Författare :Kristina Bolinder; Catarina Rydin; Jürg Schönenberger; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; växtsystematik; Plant Systematics;

    Sammanfattning : Pollination, i.e., the transport of male gametophytes to female gametophytes, can occur with biotic or abiotic vectors and is necessary for fertilization and completion of the lifecycle in all seed plants. LÄS MER

  4. 3. Evolutionary studies of the Gnetales

    Författare :Chen Hou; Catarina Rydin; Richard Saunders; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; växtsystematik; Plant Systematics;

    Sammanfattning : The Gnetales consist of three distinct genera, Ephedra, Gnetum and Welwitschia with considerable divergence among them regarding morphological, ecological and molecular characters. A longstanding debate of the similarity between the Gnetales and angiosperms and the unresolved seed plant phylogeny intrigues plant scientists to further investigate the evolutionary history of the Gnetales. LÄS MER

  5. 4. Pollen and pollination in Ephedra (Gnetales)

    Författare :Kristina Bolinder; Catarina Rydin; Johan Ehrlén; Michael S Zavada; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; aerodynamics; evolution; moonlight; pollination; pollen morphology; ultrastructure; växtsystematik; Plant Systematics;

    Sammanfattning : Ephedra (Gnetales) is a gymnosperm genus with a long evolutionary history; the first dispersed pollen grains with affinity to the group are known already from the Permian. This thesis focuses on the evolutionary history of the group and different aspects of its pollination mechanisms. LÄS MER

  7. 5. Proteomics and phylogenetics of the Gnetales

    Författare :Chen Hou; Catarina Rydin; Niklas Wikström; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; växtsystematik; Plant Systematics;

    Sammanfattning : A central point of Darwin’s theory of evolution is that accumulation of many small changes during the evolutionary process can result in significant change over time. In light of his theory, plant scientists seek for and compare different plant traits among species e.g. LÄS MER