Kingdom Plantae • 1. Bryophytes • Mosses, liverworts and hornworts. liverwort moss hornwort moss
Bryophytes Seed Plants Tracheophytes Evolutionary Treeof Major Plant Groups Liver-worts Gymno-sperms Angio-sperms Mosses Ferns Flowers & Fruits appear True vascular tissue& lignin appear Seeds andpollen appear AncestralAlgae
sporophyte gametophyte - photosynthetic
Bryophyte life cycle • Exhibit alternation of generations: they have a gametophyte and sporophyte generation • Copy diagram of life cycle
Non-vascular plants, i.e. they don’t have xylem or phloem • Advancements over algae: cuticle, multicellular gametangia, stomata • Habitat: they require moist environment for active growth and sexual reproduction
The male plant produces clusters of antheridia which contain thousands of ciliate sperm.
Bryophytes • Gametophyte generation (n) is dominant • Has green “leafy stems” and root-like structures called rhizoids, for anchoring (not true roots!) • Have stomata and cuticle • Bryophytes lack vascular tissue – do not have xylem or phloem. • This absence of vascular tissue prevents bryophytes from having true roots, stems or leaves. • Also, lack of conducting tissue limits their size.
Bryophyte reproduction • Gametophyte plant produces multicellular sex organs: • Archegonia – produces eggs (female) • Antheridia – produces motile sperm (male) • Outer layers protects and prevents drying • Motile sperm must swim to archegonia.
Bryophyte reproduction • Sporophyte occurs after egg is fertilized by sperm (2 n) • Sporophyte grows in the archegonium of the gametophyte plant – it’s dependent on it • Mature sporophyte consists of: • Foot (point of attachment) • Seta (stalk) • Capsule (spore case)
Bryophytes • Sporocytes within the Sporophyte undergo meiosis to produce a single kind of haploid spore • If spore lands on suitable place, it will germinate into a protonema, the initial stage of the gametophyte plant.
Bryophyte significance • Bryophytes are small and inconspicuous, but important part of the biosphere • Food for mammals, birds • Important to prevent soil erosion along streams • Commercially – peat moss (Sphagnum) is used as fuel, soil conditioner, by florists