Cone-bearing shoots dichasial, insect pollinated. Females subtended by cone-scales making up a red cone and consisting of a single nucellus enclosed in an integument and another layer derived from two confluent primordia ('calyx and corolla of a flower (generally used when the two are similar).">perianth') with 2 'bracts'; megaspore mother-cell grows into a prothallus without archegonia. Male microsporangia subtended by cone-scalesmaking up a red cone and consisting of 2 lateral 'bracts' and a 'perianth' formed by the union of 2 bract-like organs, 6 microsporangiophores and a sterile unitegmic ovule; male gametophyte merely a tube-nucleus, an abortive sterile cell and a cell giving rise to 2 sperm nuclei. As pollen tubes penetrate prothallus, prothallial tubes grow up to meet them in the nucellus, fusion of females and males allegedly occurring in the tubes; many zygotes but only one matures and is dispersed with 'perianth' as a wing.
An excellent article by Anna Senters can be found here
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