15. Seed habit (ovule + integument), pollen, 1 megaspore per megasporangium 16. Scalariform pitting in secondary xylem. 17. Ovules enclosed in carpels (ovary), simple gametophytes (3-celled microgametophyte, 7-celled megagametophyte), ovules with 2 integuments, sieve tube elements in phloem, formation of endosperm via double fertilization.

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