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Seed Plants Without Flowers - Gymnosperms (Division of Progymnospermophyta…
Seed Plants Without Flowers - Gymnosperms
History
seeded plants grouped into single division in 1800's
Gymnosperms
Naked Orules
Angiosperms
Flowering plants
Evolution of Seeds
Megasprangium
Integument
layer of tissue that surrounds Megasprangium
Large Microphyte
hole that allows sperm to swim to egg
Division of Progymnospermophyta
evolution of vascular cambium with unlimited growth potential of secondary Xylem and Phloem
Gave later rise to conifers and cycads
Produced woody trees
Aneurophytales
Vary in structure, from shrubs to trees
Archaeopteridales
abundant wood, and secondary phloem
Heterosporous reproduction
Division Pteridospemophyta
Early seed ferns appeared in Devonian age
3 divisions
pteridospermophyta
cycadeoidphyta
cycadophyta
Seed Ferns
Leaves similar to true fern
long lived Xylem, Phloem, and vascular cambium
Division coniferophyta
Simple needed leaves
Lack Vessels
all have simple pollen cones
seed cones and compound cones
inside Megasporangium is a large megaspore mother cell
Division Cycadophyta
most short plants with trunk covered in bark
no Ovules on leaves
seed cones vary
Division Ginkgophyta
contains single living species
Lacks vessels and Axial Parenchyma
dioecious and gymnospermous reproduction; But no cones present
Division Gnetophyta
3 groups
Gnetum
ephedra
Welwitschia Mirabilis
Vines and small shrubs
Leaves are reduced and scale like
Vessels in wood; unusual in gymonosperms
