THE SPOROPHYTE-GAMETOPHYTE JUNCTION IN HYMENOPHYTON AND SYMPHYOGYNA (METZGERIIDAE, HEPATICAE) - STRUCTURE AND PHYLOGENETIC IMPLICATIONS

The structure of the sporophyte-gametophyte junction in the Metzgerial ean liverworts Hymenophyton leptopodum and Symphyogyna subsimplex, pre sumed remnants of an old Gondwanan bryophyte flora, were studied with light, scanning, and transmission electron microscopy. As other liverw orts, both species belong to the ''intraplacental'' taxa in which the cleft between sporophytic foot and gametophyte is filled with collapse d cells of gametophytic origin. In Hymenophyton leptopodum, wall labyr inths are absent in the placental cells of both generations. We suppos e this reflects the ancestral condition of the sporophyte-gametophyte junction in the bryophytalean lineage of land plant evolution. The ver y coarse sporophytic wall ingrowths in the outermost sporophytic foot layer of Symphyogyna subsimplex correspond with those known from Palla vicinia indica and seem to represent a unique evolutionary line within liverworts.