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Published byMarjory French Modified over 9 years ago
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Section 3 – Vascular Plants
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Seedless Vascular Plants Dominated the earth until 200 million years ago Made up of 4 phyla – The ferns and the fern allies Spores are the mobile sexual reproductive part of all seedless plants Table 28-2 is a good resource
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Phylum Psilophyta The Whisk Ferns Found in tropical and subtropical regions Not actually ferns – No true roots or leaves – Produce spores on the ends of their branches Some grow on other plants – not parasites though – Called Epiphytes (grow on other plants)
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Phylum Lycophyta The Club Mosses or Ground Pines – Look like miniature pine trees Produce a strobilus (cone) – A cluster of sporangia-bearing modified leaves Selaginella lepidophylla – Native to American Southwest – Turns brown and curls into a ball during a drought Will uncurl after a few hours if moistened (Resurrection Plant)
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Phylum Sphenophyta The Horsetails (Equisetum) Grow from a rhizome Stems are hollow and have joints with scale like leaves Spores form in cones at the tip of the plant Pioneers used them as scrub brushes: Scouring rushes
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Phylum Pteridophyta The Ferns A diverse group – Multiple environments – Species range from 1 cm to 5 m across Have an underground stem called a rhizome New leaves start out tightly coiled as fiddleheads Fiddleheads develop into mature leaves called fronds
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Vascular Seed Plants Mobile sexual reproductive part is the multicellular seed Seeds are made up of: Embryo and a nutrient supply Seeds only grow under favorable conditions The seed will germinate (sprout) and grows into a seedling
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Made up of two main groups: – Gymnosperms: 4 phyla Naked seeds in a cone – Phylum Cycadophyta – Phylum Ginkgophyta – Phylum Coniferophyta – Phylum Gnetophyta – Angiosperms: 1 phylum Seeds in fruits – Phylum Anthophyta Vascular Seed Plants
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Phylum Cycadophyta The Cycads Flourished during the dinosaur era – Now only 100 species – Native to tropics Fernlike, leathery leaves on top of a short, thick trunk Are either male or female Bear large cones
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Phylum Ginkgophyta Also flourished during the dinosaur era Now only one species: Ginkgo trees – Called “The Living Fossil” Closely resembles 125 million year old ginkgo trees They are deciduous – unusual for gymnosperms Seeds are fleshy and plum-like, often mistaken for fruit (they smell REALLY bad too!)
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Phylum Coniferophyta The Conifers – Example: pine trees Woody plants with needle or scale like leaves Usually have both male and female cones – Males near the top and females near the bottom
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– Male cones typically are smaller and grow in clusters release dust-like pollen – Female cones are larger and sticky Pollen blows into the cones – they close up Seeds mature after one or two years – then release Phylum Coniferophyta
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Phylum Gnetophyta Odd group of cone bearing gymnosperms – Consist of Ephedra (look like horsetails), and Welwitschia mirabilis: and odd desert plant that’s a few cm tall and up to 1m in diameter Vascular tissue more closely resembles Angiosperms – What does that mean? Probably an evolutionary step between gymnosperms and angiosperms
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Phylum Anthophyta The angiosperms (flowering plants) – Largest phylum of plants (240,000 species) Characterized by the presence of flowers and fruit – Fruit: a ripened ovary that surrounds the seeds of angiosperms Ovary: the female part of the flower that encloses the egg Very diverse phylum: shrubs, vines, grasses, trees
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Evolution of Angiosperms More successful than Gymnosperms – Seeds germinate and produce a new mature plant in one growing season vs. up to ten years for germination and maturation – Fruits protect the seeds and aid in their dispersal – Have a more sufficient vascular system More likely associated with mycorrihizae – Animal pollination in some species rather than wind pollination – Diversity of angiosperms allows them to do more things
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Monocots vs. Dicots Monocot features One cotyledon (seed leaf) Parallel venation in mature leaves – Several main veins or bundles of vascular tissue running parallel to each other Flower parts occur in threes – Sets of three petals Dicot features Two Cotyledons (seed leaf) Net Venation in mature leaves – One or more nonparallel veins that branch repeatedly Flower parts occur in fours or fives – Sets of four or five petals
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