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Chapter 23: Seed plant I - Coggle Diagram
Chapter 23: Seed plant I
Concept
the life cycle of vascular cryptogams is an alternation of independent, heteromorphic generation
disadvantage: the new sporophyte, while developing from the zygote, is temporarily dependent on a tiny gametophyte for its start in life
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Spermatophytes: The plant that existed after the origin of wood but before that of seeds were trees that reproduced with spores.
Manoxylic wood: soft, spongy and parenchymatous wood.
Pycnoxylic wood: hard, strong wood with little parenchyma.
gymnosperms: plants with naked ovules, ovule is located on flat sporophylls.
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flowering plant with carpel which are believed to be sporophylls that forms tube-like, closed structure and fruits are mature carpel.
Division of 
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Archseopteridales
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Sporangia were terminal on short branches mixed with sterile, leaflike branch system.
Evolution of seeds
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was a large micropyle, a hole in the integument that permitted the sperm cells to swim to the egg.
the space at the top of the megasporangium became the place where microspores settled acting as pollen chamber.
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change occurred in the nature of their wall, method of germination and in the nature of the microgametophyte they produced.
Division Pteridospermophyta
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Classified as three
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cycadophyta: cycads, extant
Cycadeoidophyta: Cycadeoids, all extinct
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Tracheids were much longer and wide enough that several rows of circular boardered pith could occur in each radial wall.
leaves were larger, compound and planar
Division of
never vines, herbs or annual and never have bulbs or rhizomes
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Tracheids are so narrow that only one or two rows of circular bordered piths occur on their radial walls.
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Conifer pollen arrives before the egg is mature, and more than a year may pass between pollination and fertilization
Division Cycadophyta
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Division Cycadophyta
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trunk is covered with bark and persistent leaf bases that remain on the plant even after lamina and petiole have abscised.
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seed cone is a large, loose aggregation of leaflie, pinnatately compound megasporophylls.
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Division of Gnetophyta
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have short, wide stem and only two leaves