Plant Diversity 1 - Lecture notes 8 PDF

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Dr. Daniel Stern Cardinale...

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Plant*Diversity*1 Friday, February 10, 2017

9:09 AM

• Characteristics*of*plants ○ SEQ*evolution ○ CC*charophytes,*land*plants • Classification*of*plants ○ CC*major*groups • Bryophytes ○ CC*bryophytes ○ SEQ*moss*life*cycle • Vascular*Plants ○ CC*vascular*plants ○ SEQ*fern*life*cycle 1. Characteristics*of*land*plants a. Evolution*of*land*plants i. Evolved*from*ancestral*charophytes*(green*algae) ii. Modern*charophytes-->*sister*taxon*to*land*plants iii. Adaptations*for*land 1) Many*charophytes*live*at*edges*of*ponds 2) Sometimes*dries*out-->*selection*favors*survival*on* dry*land 3) Sporopollenin-layer*of*polymer,*surrounds*zygote* prevents*desiccation 4) Similar*adaptations*in*plant*spores iv. Derived*traits*of*charophytes*(including*land*plants) 1) Rings*of*cellulose-synthesizing*proteins 2) Structure*of*flagellated*sperm a) 2*flagella b) Important*in*terms*of*where*different*types*of* plants*can*live c) Adapt*to*different*environments

3) Formation*of*fragmoplast-groups*of*microtubules* between*daughter*nuclei 4) Presence*of*a*cell*plate a) Appears*during*cell*division b. Derived*traits*of*land*plants i. Traits*unique*to*plants ii. 7*derived*traits 1) Alternation0of0generations a) 2*multicellular*life*stages b) Separated*by*unicellular*stages c) Stage*makes*gametes d) Stage*makes*spores e) Haploid*stage*is*gametophyte i) Makes*gametes ii) Gametes*are*made*by*mitosis f) Diploid*stage*is*sporophyte (2n) i) Makes*spores ii) Produces*spores*by*meiosis g) Sporophtyes*(2n)*produce*spores**(n)*by*meiosis h) Gametophytes*n*produce*gametes*n*by*mitosis 2) Multicellular,*dependent*embryo a) 2n*embryo*retained*within*tissue*of*female* gametophyte b) Nutrients*transferred*parent-->*embryo*through* transfer*cells c) Land*plants*sometimes*called*"embryophytes" 3) Walled*spores*produced*on*sporangia a) Sporangia-multicellular*organs*that*produce* spores b) Sporocytes-diploid*cells,*undergo*meiosis-->* haploid*spores c) Spores-haploid*reproductive*cells d) Spores-->*gametophyte*by*mitosis e) Spore*wall*contains*sporopollenin i) Resistant*to*drying*out*and*harsh* conditions 4) Multicellular gametangia

4) Multicellular*gametangia a) Gametangia-multicellular*gamete-producing* organs--2*types i) Haploid*structures b) Archegonia-produce*eggs,*site*of*fertilization c) Antheridia-produce*and*release*sperm 5) Apical*meristems a) Plants*do*not*move,*do*elongate b) Apical0meristems-localized*regions*of*cell* division*at*tips*of*roots*and*shoots c) Cells*differentiate*from*apical*meristems, d) Differentiation*into*different*cells*or*tissues*will* occur*later 6) Cuticle a) Waxy*covering*over*all*above-ground*plants b) Prevents*desiccation c) Provides*some*protection*from*microbes d) Does*not*allow*for*gas*exchange 7) Stomata0 a) Tiny*openings*on*surface b) Can*open*and*close c) Allow*gas*exchange d) Underside*of*leaves*or*on*the*stem e) Allow*water*evaporation 2. Classification*of*land*plants ○ Can*group*extant*plants*based*on*vascular0tissue:*cells*joined* into*tubes,*transport*water*and*nutrients a. Nonvascular0plants i. Bryophytes-mosses*and*relatives ii. Lack*specialized*vascular*systems iii. Ancestral*state-paraphyletiic*group iv. Not*monophyletic--not*a*clade b. Vascular0plants i. Seedless*and*seed*plants ii. Seedless*vascular*plants*(not*a*clade) iii. Lycophyes-club*mosses iv. Monilophytes-ferns

c. Seed0plant i. Majority*of*extant*plant*species--2*groups ii. Seed-embryo*with*supply*of*nutrients*within*protective* coat iii. Gymnosperms 1) Naked*seed 2) Seeds*not*enclosed*in*a*chamber 3) Ex.*Conifers iv. Angiosperms 1) Container*seed 2) Flowering*plants 3) Seeds*enclosed*in*fruit 4) Most*dominant*type*of*plant 3. Bryophytes a. Characteristics i. Small,*herbaceous*(non-woody) ii. Phylum*Hepatophyta-liverworts iii. Phylum*anthocerophyta-hornworts iv. Phylum*Bryophyta-mosses v. Early*divergence*of*bryophytes vi. Nonvascular 1) No*specialized*transport*tissue 2) Do*not*have*roots 3) Rely*on*diffusion,*osmosis 4) Typically*small 5) Require*moist*environment*for a) Water b) Reproduction b. Bryophyte*life*cycle § Gametophyte-gamete*forming*plant*(haploid) § Protonema-filament*of*haploid*cells □ Looks*like*hyphae*in*fungi § Gametophores-gamete-producing*structures § Rhizoid-anchors*gametophyte*in*ground-not*roots § Antheridium-sperm*producing*structure § Archegonium-egg-producing*structure i. Moss life cycle fig 29.6

i. Moss*life*cycle*fig*29.6 1) Spores-haploid*reproductive*cells a) Dispersed*through*environment b) Germinate*into*protonema 2) Grow*into*male*gametophyte*structure 3) Antherida-sperm*made*inside 4) Archedonia*house*eggs*in*female*gametopyte 5) Need*to*be*in*watery*environment*in*order*for*sperm* to*swim*to*egg 6) Fertilization*within*archegonia 7) End*with*zygote § Sporophyte-spore*forming*plant*(diploid) § Foot-anchors*to*gametophyte § Seta-stalk-connects*foot*to*capsule § Capsule-sporangia,*spore*producing*structure § Peristome-upper*part*of*capsule,*ring*of*interlocking* tooth-like*structures--releases*spores*under*right* conditions ii. Moss*life*cycle*diploid*stage 1) Zygote*inside*archedonium 2) Embryo 3) Young*sporohyte*(2n) 4) Female*gametophytes 5) Spore*released*into*environment c. Importance*of*mosses i. Extremely*common ii. Can*colonize*bare,*sandy*soil iii. Help*retain*N*in*soil iv. Sometimes*harbor*N-fixing*bacteria v. Peat-partially*decayed*organic*matter vi. Peat*moss*is*important*component vii. Important*fuel*source viii. 3%*of*Earth's*surface,*30%*of*C*in*soil-->*important*C* reservoir 4. Vascular*plants ○ Earliest*fossil*425*mya ○ Dominant*today

a. Derived*traits*of*vascular*plants i. Sporophyte*dominant*(diploid*dominant*in*their*life* cycles)*--larger,*independent ii. Transport*in*vascular*tissue-have*lignin 1) Lignin-polymer*in*cell*walls*of*water*conducting*cells iii. Enables*tall*growth 1) Tall-->*outcompete*shorter*plants*for*light,*better* spore*dispersal iv. Xylem-conducts*water*and*minerals--contains*lignin v. Phloem-conducts*sugars,*AAs,*organic*products vi. Roots-organs*that*absorb*water*and*nutrients*from*soil,* anchor*plants 1) Allow*for*taller*growth vii. Leaves-primary*photosynthetic*organs,*increase*surface* area viii. Sporophylls-modified*leaves*with*sporangia 1) Very*diverse 2) Ferns-sori 3) Gymnosperms-cones ix. Spore*variations--2*forms*of*spore*production 1) Homosporous-1*type*of*sporangium*and*spore a) Most*seedless*vascular*plants b) Spore-->*bisexual*gametophyte 2) Heterosporous-2*types*of*sporangia*and*spores a) Megasporangium-produces*megaspores i) Female*gametophyte-->*egg*in*archegonia b) Microsporangium-produces*microspores i) Male*gametophyte-->*sperm*in*antheridia b. Classification*of*seedless*vascular*plants i. 2*clades ii. Lycophytes-earliest*vascular*plants iii. Many*are*epiphytes-use*other*plants*as*substrate,*ot* parasitic 1) Grow*on*surgace*of*trees iv. Monilophyes-ferns,*most*common*seedless*vascular...