3 Bryophytes There are three groups of bryophytes Mosses 12,000 species Liverworts 6,500 speciesHornworts 100 species
4 Bryophyte diversity Hornworts 100 species Liverworts 6,500 species Mosses12,000 species
5 Mosses Mosses - 12,000 species Widely distributed, especially in alpine, boreal,temperate, and tropical forestsAble to live in very dry or very cold habitatsMany can dry out entirely, then rehydrate
6 Famous mosses: Sphagnum Wetland moss -“peat moss”Boggy regions dominated by it known as peat bogs or peatlands
7 Liverworts and hornworts Liverworts are even less conspicuous than mosses. Some have a lobed appearance.They reproduce both sexually and asexually from small bundles of cells known as gemmae.Hornworts have elongated sporophytes that are hornlike in appearance. They are unusual in that each photosynthetic cell contains one large chloroplast rather than many smaller ones.
8 BryophytesBryophytes arose at least 400 mya and possess two adaptations that allow them to survive on land.Waxy cuticle reduces water lossGametes are protected and develop within gametangia.
9 BryophytesBryophytes do not have a vascular system and so cannot grow very large.They also need moisture to reproduce because fertilization depends on sperm being able to swim through water to reach the egg.
16 Bryophyte life cycle 2n n meiosis sporophyte spores embryo gametophyte zygoteeggssperm
17 Bryophyte reproduction Spores produced in capsule (sporangium)Spores released to germinate into gametophytes.
18 Bryophyte reproduction Male gametophytes produce sperm and female gametophytes produce eggs.When there is sufficient moisture sperm swim to the egg and fertilize it. Fertilized egg develops into a zygote and ultimately into a sporophyte.
21 Seedless vascular plants: Ferns and fern allies First vascular plants originated about 420 mya.First seed plants came later about 360 mya.Seedless vascular plants dominated the planet during the Carboniferous period ( mya).21
22 Seedless vascular plants: Ferns and fern allies Giant tree ferns, horsetails and lycopods were the dominant vegetation of the Carboniferous period.Their fossilized remains formed extensive coal beds.They were ultimately superseded by the seed plants and far fewer survive today.
23 Present day fern allies Lycopods: About 1,000 species. Includes tropical epiphytes and northern hemisphere low growing club mosses.Horsetails: today about 15 species of Equisetum occur in northern hemisphere in damp conditions.
37 Fern morphology Free-living gametophyte Also called a prothallus Produces sperm and eggsSporophyte starts attached to gametophyte. Gametophyte dies after sporophyte detaches.Sporophyte37
38 Spores and seedsThe spores of ferns are tiny and vast numbers are produced. However, their prospects of survival are low.A new evolutionary innovation, the seed, arose in the Carboniferous Period. Seeds and later fruit proved to be enormously successful and seed plants especially angiosperms came to dominate the planet.