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Seed plants without flowers I (Gymnosperms) - Coggle Diagram
Seed plants without flowers I (Gymnosperms)
Division progymnospermophyta: Progymnosperms
Aneurophytales
They varied in statue from shrubs to large trees, up to 12m tall. They all had vascular cambium and secondary growth, but the primary xylem of their stems was a protostele like that of rhyniophytes
Archeaopteridales
These were trees up tp 8.4m tall with abundant wood and secondary phloem stems of archaeopteris, pith surrounded by a ring of primary xylem bundles, much likemodern conifers and eudicots
Evolution of seeds
Integument
A tough outer protective layer of tissue
Micropyle
a small opening in the surface of an ovule, through which the pollen tube penetrates, often visible as a small pore in the ripe seed.
Pollen chamber
In gymnosperms is a cavity in the ovule in which pollen grains are deposited after pollination. The generative cell nucleus separates within the pollen chamber to create two gametic nuclei and the cell of the tube elongates to form the pollen tube.
The earliest known Progymnospermsspecies is Chauleria from the middle devonian period approximately 390 million years olds
Progymnosperms
Group of extinct plants believed to have been the ancestors of gymnosperms
Division pteridospermophyta: Seed frems
Seed ferns
Any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores.
Pteridospermophyta are thought to have evolved from the Aneurophytales because the earliest seed ferns, had three ribbed prorstele as in the aneurophytes
Seed ferns had a long lived vascular cambium that produced both xylem and phloem this is also similar to gymnosperms and angiosperms
Leaves of seed ferns were similar to those of true ferns in overall organization- large, compound and plannar. Unlike ferns the foliage leaves of seed ferns bore seeds.
Division Ginkgophyta: maidenhair tree
This division contains a single living species - ginkgo biloba because of how unusual it is
It 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 it has broad leaves but they have dichotomously branched veins like seed ferns, not reticulate venation like dicots
Ginkgo have both short shoots, which bear most of the leaves and long shoots
Division coniferophyta: Conifers
They are diverse (approximately 50 genera and 550 species) and they all are trees of moderate to gigantic size; redwoods of california reach 90m in height and 10m in diameter
Conifer are never vines,herbs, or annuals, and they never have bulbs or rhizomes. COnifer leaves are always simple needles or scales. Leaves of most conifer are perennial, persisting for many years even on very old trunks
Pines like other conifers have two types of shoot, Tiny papery leaves appear of long shoots and in their axils are short shoots that produce the familiar long needle leaves
Pines also have both pollen cones and seed cones. Pollen cones are simple cones with a single short unbranched axis that bears microsporophylls. The seed cones are more complex than pollen cones, they are compound cones each the consist of a shoot with axillary buds.
Division cycadophyta: cycadeoids
The cycadeoids (extinct) had vegetative features almost identical to those of cycads. The two groups differ only in subtle details of the differentiation of the stomatal complexes and in leaf trace organization.
Division Cycadophyta: Cycads
They have stout trunks with pinnately compound leave, most cycads are short plants less than or 2 m tall but Macrozamia can reach heights of 18m.
The trunks are coved with bark and persistent leaf bases that remain on the plant even after the lamina and petiole have abscised.
Cycad stems are similar to those of seed ferns, thick cortex containing secretory ducts surrounds a small amount of manoxylic
Cycad foliage leaves do not bear ovules, instead cycads produce seed cones and pollen cones, each on sperate plants; cycads are always dioecious
