Transcript Seedless Plants

Seedless Plants
Chapter 26
Plant Adaptations to Land
 Cuticle
 Waxy covering on leaves that helps prevent
desiccation
 Stomata
 Pores on the surface of leaves that allow
CO2 exchange
 Gametangia
 Multicellular sex organs which develop
multicellular embryos
Alternation of Generations
 Gametophyte generation
 Haploid
 Produces haploid gametes by mitosis
 Sporophyte generation
 Diploid – begins when haploid gametes fuse
 Produces haploid spores by meiosis
Major Groups of Land
Plants
 Bryophytes
 Small, nonvascular
 Mosses
 Seedless vascular plants
 Contain tissues to conduct water and food
 Ferns
 Gymnosperms
 ‘Naked seeds’
 Conifers
 Angiosperms
 Flowering plants
 Most plants are in this group
Bryophytes
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Over 15,000 species
Nonvascular – must remain small
Require moist habitats
Three main groups:
 Mosses
 Liverworts
 hornworts
Mosses
 No true leaves, stems, or roots due to
lack of vascular tissue
 Rhizoids – tiny absorptive structures
which have a similar function as roots
 Upright leaf-like structures
 Environmental importance:
 Help in soil formation
 Sphagnum moss – useful in gardening
Liverworts
 Flattened body form called a thallus
 Thallus is ‘liver’ shaped
 Rhizoids on the underneath side of
thallus
Hornworts
 Resemble liverworts
 Live in disturbed habitats
Seedless Vascular Plants
 Ferns, whisk ferns, horsetails, club
mosses
 Specialized vascular tissue:
 Xylem – conducts water
 Phloem – conducts dissolved sugars
 Allows this group to be larger than the
bryophytes
Ferns
 Mostly terrestrial
 Clearly defined alternation of generations
 Rhizome – underground stem which
supports a true leaf and roots
 Frond – the leaf
 Spores are produced on the underside of
the frond
Whisk Ferns
 The simplest vascular plants
 Lack true roots and leaves but have
vascularized stems
Horsetails
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Have hollow, jointed stems
Were the dominant plants 300 mya
Major contribution to coal deposits
Have true roots, stems, and small leaves
Were used as ‘scouring rushes’
Club Mosses
 Also part of modern day coal deposits
 Attractive – often used as Christmas
wreaths