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CH 21 Part 2

CH 21 Part 2. Phylum Equisetophyta – The Horsetails and Scouring Rushes. Equisetum Branched and unbranched forms, usually less than 1.3 meters tall Stems jointed and ribbed. If branched, then branches in whorls. Scalelike leaves in whorls at nodes. Stomata in grooves between ribs.

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CH 21 Part 2

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  1. CH 21 Part 2

  2. Phylum Equisetophyta – The Horsetails and Scouring Rushes • Equisetum • Branched and unbranched forms, usually less than 1.3 meters tall • Stems jointed and ribbed. • If branched, then branches in whorls. • Scalelike leaves in whorls at nodes. • Stomata in grooves between ribs.

  3. Phylum Equisetophyta • Stem anatomy: • Hollow central cavity from break down of pith • Two cylinders of smaller canals outside pith. • Carinal canals conduct water with xylem and phloem to outside. • Vallecular canals outside carinal canals contain air. • Silica deposits on walls of stem epidermal cells.

  4. Phylum Equisetophyta • Equisetum reproduction: • Asexual by fragmentation of rhizomes • Sexual reproduction: • Strobili at tips of stems with sporangia connected to sporangiophores. • Spores green with 4 ribbon-like elaters attached. • Aid in spore dispersal • Gametophytes lobed, green, cushionlike, up to 8 mm in diameter. Spores with elaters

  5. Phylum Equisetophyta • Equisetum reproduction:

  6. Phylum Equisetophyta • Ancient relatives of horsetails: • Flourished in Carboniferous, 300 million years ago. • Human and ecological relevance: • Many giant horsetails used for food by humans and other animals. • Scouring rush stems used for scouring and sharpening. Reconstruction of fossil giant horsetail, Calamites

  7. Phylum Polypodiophyta – The Ferns • Structure and form: • Vary in size from tiny floating forms less than 1 cm to giant tropical tree ferns up to 25 m tall • Fern leaves are megaphylls - Referred to as fronds. • Typically divided into smaller segments • Require external water for reproduction

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