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Ch. 23: Seed plants without flowers - Coggle Diagram
Ch. 23: Seed plants without flowers
Concepts
Lifecycle of vascular cryptograms is an alternation of independent, heteromorphic generations. A disadvantage of this life cycle is that the new sporophyte, while developing from the zygote, it's temporary dependent on a tiny gametophyte for its start in life
Lignophytes- monophyletic Group of woody plants.
spermatophytes
- Type of seed plant
Division Progymnospermophyta: progymnosperms
One group to evolve from trimerophytes was the now extinct progymnosperms
The vascular cambium of this was able to produce virtually unlimited amounts of both secondary xylem and secondary phloem. It had very large vertical tracheids with pitted walls and an abundance of rays with Ray tracheids
The earliest known progymnosperm Is from about 390 million years ago. They produced only one megaspore mother cell, and is produced only one large, viable megaspore and three small aborted cells.
The megasporangium Was surrounded by a layer of tissue, and
integument
, that projected upward. There was a large
micropyle
Division: Pteridospermophyta: seed ferns
The earliest seen Burns appeared in the upper Devonian period. Not all are closely related to each other; they form a grade rather than a clade. Seed ferns were any woody plant with Fern like foliage That bore seeds instead of sori (clusters of sporangia) on its leaves
Leaves of seed Ferns were similar to those of true friends and overall organization-large, compound, and planar
Division Coniferophyta: Conifers
Pines, like several other conifers have two types of shoot each with a characteristic type of belief. Tiny paper relieves occur on long shoots and in their axils are short shoots That produce the familiar long needle leaves.
Pollen cones are simple cones with a single short unbranched axis that bears microsporophylls
Seed cones are more complex than pollen cones: they are compound cones, each consisting of a shoot with axillary buds. The short axis bears leaves called cone bracts
A zygote does not immediately form an embryo in conifers; Instead, some of the first cells elongate as a
suspensor
that pushes the other cells deep into this megagametophyte. These other cells called the proembryo develops into the embryo
Division Cycadophyta: Cycads
They have scout trunks with pinnately compound leaves. The foliage leaves do not bear ovules
Do you see the county is a large, at least aggregation with like pinnately compound megasporophyll.
Division Cycadeoidophyta: Cycadeoids
Although all extinct, they had vegetative features almost identical to those of cycads. Between the ovules were thick, fleshy scales.
Division Ginlgophyta: Maidenhair Tree
This division contains a single living species. The species is very unusual and looks very much like a large dicot Tree with a stout trunk and many branches, but its wood is like that of conifers. It lacks vessels and axial parenchyma.
Division Gnetophyta
Gnetums are mostly vines or small shrubs with broad leaves similar to those of dicots. They are native to south east Asia, tropical Africa common and the Amazon basin.
The pollen cones are compound and contains small bracts. Seed cones are also compound and contain extra layers of tissue around the ovules.
