Seedless PlantsSeedless Plants

Chapter 26Chapter 26

Plant Adaptations to Plant Adaptations to LandLand

CuticleCuticle Waxy covering on leaves that helps prevent Waxy covering on leaves that helps prevent

desiccationdesiccation Stomata Stomata

Pores on the surface of leaves that allow Pores on the surface of leaves that allow CO2 exchange CO2 exchange

Gametangia Gametangia Multicellular sex organs which develop Multicellular sex organs which develop

multicellular embryosmulticellular embryos

Alternation of Alternation of GenerationsGenerations

Gametophyte generationGametophyte generation HaploidHaploid Produces haploid gametes by mitosisProduces haploid gametes by mitosis

Sporophyte generationSporophyte generation Diploid – begins when haploid gametes fuseDiploid – begins when haploid gametes fuse Produces haploid spores by meiosisProduces haploid spores by meiosis

Major Groups of Land Major Groups of Land PlantsPlants

BryophytesBryophytes Small, nonvascularSmall, nonvascular MossesMosses

Seedless vascular plantsSeedless vascular plants Contain tissues to conduct water and foodContain tissues to conduct water and food FernsFerns

GymnospermsGymnosperms ‘‘Naked seeds’Naked seeds’ ConifersConifers

AngiospermsAngiosperms Flowering plantsFlowering plants Most plants are in this groupMost plants are in this group

BryophytesBryophytes

Over 15,000 speciesOver 15,000 species Nonvascular – must remain smallNonvascular – must remain small Require moist habitatsRequire moist habitats Three main groups:Three main groups:

Mosses Mosses LiverwortsLiverworts hornwortshornworts

Mosses Mosses

No true leaves, stems, or roots due to No true leaves, stems, or roots due to lack of vascular tissuelack of vascular tissue

Rhizoids – tiny absorptive structures Rhizoids – tiny absorptive structures which have a similar function as rootswhich have a similar function as roots

Upright leaf-like structures Upright leaf-like structures Environmental importance:Environmental importance:

Help in soil formationHelp in soil formation Sphagnum moss – useful in gardeningSphagnum moss – useful in gardening

LiverwortsLiverworts

Flattened body form called a thallusFlattened body form called a thallus Thallus is ‘liver’ shapedThallus is ‘liver’ shaped Rhizoids on the underneath side of Rhizoids on the underneath side of

thallusthallus

HornwortsHornworts

Resemble liverwortsResemble liverworts Live in disturbed habitatsLive in disturbed habitats

Seedless Vascular PlantsSeedless Vascular Plants

Ferns, whisk ferns, horsetails, club Ferns, whisk ferns, horsetails, club mossesmosses

Specialized vascular tissue:Specialized vascular tissue: Xylem – conducts waterXylem – conducts water Phloem – conducts dissolved sugarsPhloem – conducts dissolved sugars

Allows this group to be larger than the Allows this group to be larger than the bryophytesbryophytes

FernsFerns

Mostly terrestrialMostly terrestrial Clearly defined alternation of generationsClearly defined alternation of generations Rhizome – underground stem which Rhizome – underground stem which

supports a true leaf and rootssupports a true leaf and roots Frond – the leafFrond – the leaf Spores are produced on the underside of Spores are produced on the underside of

the frondthe frond

Whisk FernsWhisk Ferns

The simplest vascular plantsThe simplest vascular plants Lack true roots and leaves but have Lack true roots and leaves but have

vascularized stemsvascularized stems

HorsetailsHorsetails

Have hollow, jointed stemsHave hollow, jointed stems Were the dominant plants 300 myaWere the dominant plants 300 mya Major contribution to coal depositsMajor contribution to coal deposits Have true roots, stems, and small leavesHave true roots, stems, and small leaves Were used as ‘scouring rushes’Were used as ‘scouring rushes’

Club MossesClub Mosses

Also part of modern day coal depositsAlso part of modern day coal deposits Attractive – often used as Christmas Attractive – often used as Christmas

wreathswreaths