Green Plants Biol 366 Spring 2011. Tree of Life: The Big Picture EukaryotesArchaeaBacteria ca. 4 bya...
-
Upload
nicholas-merritt -
Category
Documents
-
view
217 -
download
0
Transcript of Green Plants Biol 366 Spring 2011. Tree of Life: The Big Picture EukaryotesArchaeaBacteria ca. 4 bya...
Green Plants
Biol 366
Spring 2011
Tree of Life: The Big Picture
EukaryotesArchaeaBacteria
ca. 4 bya
now
>3.5 bya
>2 bya
membrane-boundnucleus, organelles, etc.
Fig. 7.1 from the text
Green plants share:
• Chlorophylls a and b
• Starch storage
• Stellate flagellar structure
• Certain gene transfers from the chloroplast to the nucleus
Green plant diversity:
• > 300,000 species
• Two major groups: 1) chlorophytes (marine and other green algae) and 2) streptophytes [freshwater green algae and embryophytes (= land plants)]
• A major branch (clade) in the eukaryotic Tree of Life
Fig. 7.2 from the text
Basal streptophytes: Fig. 7.4 from the text
Chlorophytes: Fig. 7.3 from the text
Conjugation inSpirogyra
Haplontic life cycle (haploid dominantor zygotic meiosis)
The only diploid cellthe zygote
CharalesHaplontic but some havemulticellular gametangia(gamete-producing structures)
Embryophytes (land plants) share:
• Cuticle• Alternation of generations (multicellular
sporophyte and multicellular gametophyte)
• Multicellular gametangia (gamete-producing structures)
• Multicellular sporangium (spore-producing structure)
• Embryo (young sporophyte)
Bryophytes
• Hornworts, liverworts, mosses• Gametophyte-dominant• No vascular tissue (except conducting
cells in a few mosses)• Separate male and female
gametophytes• Sperm must swim to the egg, therefore
need water for fertilization and therefore must remain small
Fig. 7.5 from the text: liverworts, mosses and hornworts
Fig. 7.6 from the text
Hornwort sporophytes and gametophytes
Liverwort thallus (gametophyte) showing air pores
LiverwortMulticellular gametangia(male = antheridia)
LiverwortMulticellular gametangia (female = archegonia)OogamyRetention of zygote within the female gametophyteMulticellular embryo
Moss male gametophyte(= antheridia)
Capsule = sporangium of the sporophyte
Tracheophytes (vascular plants)
• Vascular tissue (tracheids) present
• Include lycophytes, monilophytes (ferns, horsetails, whisk ferns), and spermatophytes (seed plants)
Fig. 7.8 from the text
Monilophytes and Lycophytes
• Ferns, horsetails, quillworts, whisk-ferns, etc.
• Independent gametophytes and sporophytes
• Sperm must still swim to the egg• Most are homosporous; a few evolved
heterospory• Many homosporous ferns have means
of avoiding self-fertilization
Lycophytes
Selaginella
Lycopodium and friends
Isoetes (quillwort)
Whisk-fern (Psilotum)
Ferns (Leptosporangia)
Monilophytes (ferns, horsetails, whisk ferns)
horsetails
1n spores
Gametophyte (1n)
Sporophyte (2n)
Nutritionally independentsporophytes andgametophytes
Fern Life Cycle
Fig. 8.4 from the text
Spermatophytes(seed plants)
• Secondary xylem (wood), heterospory, seeds
• Includes gymnosperms and angiosperms
Fig. 7.12 from the text
Gymnosperms
• Conifers, gingko, cycads, Gnetales• Heterosporous (male and female sporangia)• Sporophyte-dominant• Antheridia lost, replaced by pollen (= male
gametophyte)• Archegonia present but reduced, embedded
in nutritive tissue of the megasporangium (+ integument = ovule)
• Bear seeds (= fertilized, embryo-containing, unopening ovule)
Female cone with each scalebearing usually two ovules; directly exposed to pollen
Male cones with eachscale bearing two or more microsporangia
Section of female pine cone
pine pollen
pine microsporangia
Pine seeds
Pine seedling—next sporophyte generation
Angiosperms
• “Dicotyledons”, monocotyledons• Heterosporous• Sporophyte-dominant• Pollen = male gametophyte• Archegonia lost; embryo sac = female
gametophyte; ovules enclosed in carpels (indirect pollination)
• Double fertilization produces zygote + primary endosperm nucleus
Flower = a short, determinate shoot bearing highlymodified leaves, some of which are fertile (i.e.,bearing either microsporangia or megasporangia),with the megasporangia in carpels
Fig. 4.17 from the text: Angiosperm life cycle
Animal pollination syndromes
Wind pollination