Lab__5_-_Land_plants

Lab__5_-_Land_plants - Land plants: the Bryophytes and...

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Land plants: the Bryophytes and Seedless Vascular Plants-Ferns and Fern Allies By Ioana Dobre
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Bryophytes non-vascular plants, relatively small Display alternation of heteromorphic generations : with gametophyte (n) being the dominant generation over the sporophyte (2n) Lack xylem, phloem No true roots, stems or leaves All bryophyte plant bodies are examples of a thallus (term to describe any plant body undifferentiated into stem, roots and leaves) Phylum Hepatophyta: i.e Liverworts - e.g Marchantia - Gemma cups ->> The upper surface of the thallus (plant body) produces cup-shaped structures called gemma cups. Groups of cells (called gemma ) within the cups are capable of breaking off and producing a new plant. - On ventral surface there are many rhizoids i.e tubular structures of one or more cells that anchor the thallus to the substrate - Gametophytes are unisexual  each plant has its own gender - The antheridia occur on disk-headed branches i.e antheridiophores - Archegonia occur on spoke-headed branches i.e archegoniophores - Each antheridium consistists of a short stalk and body of spermatogenous tissue surrounded by a sterile jacket layer - Antheridia are on the top surface - mitosis produces the haploid sperm
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- Archegonial heads -> venter, egg cell within venter, elongate neck with neck canal cells They’re found on the lower surface of the archegoniophore Antheridial disk serves as a ‘ splash platform ’ for raindrops Sporophyte is dependent on gametophyte and it is diploid It is attached to the gametophyte by a large foot which grows through the base of the venter into the storage tissue of the archegonial head Sporophyte also has a stalk/seta , and a capsule/ sporangium Calyptra = old archegonium
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Chlorenchyma tissue (with chlorophyll) Parenchymatous cells
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Cross-section through the lower side of the thallus showing a section through a scale and rhizoids in cross-section Rhizoids – tubular structures of one or more cells that anchor the thallus to the substrate Gemma cups Gemma cup close-up
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Antheridiophore – prepared slide l.s
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Lab__5_-_Land_plants - Land plants: the Bryophytes and...

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