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CO 20. Fig. 20.1. Fig. 20.2. Outline. Introduction Phylum Hepaticophyta - Liverworts Leafy Liverworts Phylum Anthocerophyta - Hornworts Phylum Bryophyta - Mosses. Introduction. About 23,000 species of bryophytes. Include mosses, liverworts, and hornworts.
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Outline • Introduction • Phylum Hepaticophyta - Liverworts • Leafy Liverworts • Phylum Anthocerophyta - Hornworts • Phylum Bryophyta - Mosses
Introduction • About 23,000 species of bryophytes. • Include mosses, liverworts, and hornworts. • Habitats range in elevation from sea level up to 5,500 m or more. • Bryophytes of all phyla often have mycorrhizal fungi associated with their rhizoids. • In some instances, fungi apparently are at least partially parasitic.
Introduction • Peat mosses are ecologically important in bogs. • Luminous mosses are found in caves and in other dark, damp places. • None have true xylem or phloem. • Many have hydroids. • Exhibit alteration of generations.
Phylum Hepaticophyta • Liverworts • Structure and Form • Most common liverworts have flattened, lobed thalli. • Gametophyte stage develops from spores. • When spores germinate they may produce immature gametophyte (protonema).
Phylum Hepaticophyta • Thalloid Liverworts • Best known species are in the genusMarchantia. • Thick thallus that forks dichotomously as it grows. • Consists of parenchyma cells with few, if any, chloroplasts.
Leafy Liverworts • Always have two rows of partially overlapping “leaves” whose cells contain distinctive oil bodies. • Often have folds and lobes. • Archegonia and antheridia are produced in cup-like structure. • At maturity, sporophyte capsule may be pushed out as the seta elongates. • Germinating spore produces a protonema.
Phylum Anthocerophyta • Hornworts • Structure and Form • Mature sporophytes look like miniature greenish-blackish rods. • Only about 100 species worldwide. • Thalli have pores and cavities filled with mucilage, that often contain nitrogen-fixing bacteria.
Hornworts • Asexual Reproduction • Fragmentation • Separation of lobes from thallus. • Sexual Reproduction • Archegonia and antheridia are produced in rows beneath the upper surface of the gametophytes. • Have both unisexual and bisexual plants.
Phylum Bryophyta • Mosses • Structure, Form, and Classes • About 15,000 species of mosses currently known. • Divided into three classes: • Peat Mosses • True Mosses • Rock Mosses
Mosses • “Leaves” of moss gametophytes have no mesophyll tissue, stomata, or veins. • Blades are nearly always one-cell thick, and are never lobed or divided. • Initially formed in three ranks and usually end up appearing to be arranged in a spiral or alternately on an axis that twists as it grows. • Sexual Reproduction:
Phylum Bryophyta • Human and Ecological Relevance • Pioneer Species of Primary Succession • Indicators of Surface Water • Packing Material • Peat Mosses • Soil Conditioner • Poultice Material • Fuel
Review • Introduction • Phylum Hepaticophyta - Liverworts • Leafy Liverworts • Phylum Anthocerophyta - Hornworts • Phylum Bryophyta - Mosses