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松杉類裸子植物的大孢子葉球理論評述
Theories about the seed scale of conifers are reviewed. The classical Foliar Nature theory of Delpino & Penzig suggested that the ovuliferous scales in pine are homologous to the foliar appendages of a cone axis. The Ligular theory of Sachs & Eichler maintained that the seed scale of conifers is comparative to a ligule, because it grows out from a foliar organ, namely the bract. Bessey thought that the seed scale of conifers is the combined outgrowths of an ovule from its chalazal end, which is a sui generis structure thereafter. Kubart misproposed the aril nature of the ovuliferous structure in Juniperus. Arber’s Partial-Shoot theory held that an ovuliferous scale is homologous to a simple and limited shoot (a partial shoot) based on the Telome theory, but Meeuse remarked that the Telome theory was abused here. Dupler emphasized the integumental nature of the ovuliferous scales in taxads. The Brachyblast theory of Braun has increasingly convinced the present botanists on account of excellent studies from teratology, anatomy, ontogeny and palaeobotany. Based on the established evidence from teratology, anatomy, ontogeny and palaeobotany, the present authors believe that the seed scales of living conifers may have evolved from the secondary reproductive branches of the early conifers by phylogenetic metamorphism and fusion, and little differentiation during ontogeny in the living representatives.
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