Lyginopteridopsid plants with bilateral symmetrical ovules, and with nucellus free from integument except in the basal one-fifth of the ovule; ovules noncupulate, borne on abaxial surface of unmodified pinnules; nucellar beak lacks a cellular plug or column. Male: Pollen-bearing organs consisting of 2-8 basally fused sporangia
Eustelic gymnosperms with fern-like leaves and leaf-borne reproductive organs. Cardiocarpalean ovules; microsporangia fused as a radial ring forming a synangium, dehiscence via a longitudinal slit on the inward-facing sporangial wall. Pollen saccate, with distal germination; microgametophyte forming an axial row of cells prior to sporangial dehiscence and a probable siphonogamous pollen tube at maturity. Pollination via pollination drop mechanism.
systematic position:
pteridosperms
typeseries:
Callistophytaceae
Scratchpads developed and conceived by (alphabetical):
Ed Baker,
Katherine Bouton
Alice Heaton
Dimitris Koureas,
Laurence Livermore,
Dave Roberts,
Simon Rycroft,
Ben Scott,
Vince Smith