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Biology LibreTexts

20.4: Anthocerotophyta - Hornworts

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    • Gametophyte Morphology:
      • Exclusively thalloid, often with compartments of mutualistic cyanobacteria from the genus Nostoc
      • Hornwort cells are monoplastidic, containing one large chloroplast in each cell
      • Simple pores allow for gas exchange (no guard cells, meaning pores are permanently open)
    • Sporophyte Morphology:
      • Linear sporangium that lacks a seta
      • Grows from a basal meristem
      • Stomata present for gas exchange

    If available, observe an Anthoceros gametophyte with sporophytes under the dissecting microscope. Look for simple pores, rhizoids, Nostoc colonies, sporangia, and stomata on the sporangia. Draw/label these features in the space below.

    Which part of the sporangium is the oldest? How do you know?

    Make a wet mount of a small piece of hornwort thallus or obtain a prepared slide. Can you tell how many chloroplasts are in it? Draw this cell in the space below and label the chloroplasts and any other features you recognize.

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