seedless plants eukaryotes diplomonads parabasalids ta
TRANSCRIPT
6/25/19
1
• Seedless Plants and transition to land – Origin of plants – Alternation of generations
• Spores and gametes
• Bryophytes – Mosses, liverworts, hornworts – General Life cycle
• Vascular system allows plants to get tall – Lycophytes – Ferns etc – Life cycle
26 June 2019
Silurian
Seedless Plants Eukaryotes Diplomonads
Parabasalids
Euglenozoans
Stramenopiles
Alveolates
Rhizarians
algae G
reen
Am
oebozoans Opisthokonts
Excavata
Diatoms
Golden algae
Brown algae
Dinoflagellates SAR
Apicomplexans
Ciliates
Radiolarians
Forams
Cercozoans
Red algae
Chlorophytes
Charophytes
Plants
Slime molds
Tubulinids
Entamoebas
Nucleariids
Fungi
Choanoflagellates
Animals
Unikonta
Archaeplastida
Ch 29-30 Plants, etc è
Green Algae Red Algae
Glaucophytes (unicellular)
Red Algae
“Green Algae”
6/25/19
2
Derived Traits of Land Plants Some key traits appear in nearly all land plants but
are absent in the charophytes: • Alternation of generations • Walled spores produced in sporangia • Multicellular gametangia • Waxy cuticle
Alternation of Generations
Gametophyte (n)
Gamete from another plant
n
n
Mitosis
Gamete
FERTILIZATION MEIOSIS
Mitosis
Spore n
n
2n Zygote
Mitosis
Sporophyte (2n)
Water-borne spores → protected spores
475-million year old
spore fossils!
Trilete spores of Lycopodium
475-million year old
spore fossils!
Protective organs for gamete production
Archegonium – eggs Antheridium - sperm
Fig. 29-5e
Apical meristem of shoot
Developing leaves
Apical meristems
Apical meristem of root Root 100 µm 100 µm Shoot
6/25/19
3
cuticle
The first land plants were probably moss-like
(bryophytes) plants N
onvascular
Plants
Liverworts
Origin of land plants (about 470 mya) ANCESTRAL GREEN ALGA
Mosses
Hornworts
plants vascular Seedless
Vascular plants
Lycophytes
Origin of vascular plants (about 425 mya) Ferns, etc
Gymnosperms Origin of seed plants (about 360 mya)
Angiosperms
500
Seed plants
450 400 350 300 50 0 Millions of years ago (mya)
1
2
3
Seedless Plants Silurian
Bryophytes
• Liverworts • Hornworts • Mosses
Mosses Haploid (n) Diploid (2n)
Sperm Antheridia
Male gametophyte (n)
Egg
Spores
Embryo
2 m
m
Zygote (2n)
Archegonia Female gametophyte (n)
Sporangium
MEIOSIS Mature sporophytes
Female gametophytes
Young sporophyte (2n)
Moss Life Cycle
Fertilization
6/25/19
4
The empty niche – vertical growth
• Key innovation – vascular tissue for movement of nutrients against gravity
xylem
phloem
Fossil vascular plant (420 million years ago)
Branching, independent sporophyte
Vascular system allowed the evolution of wood and leaves
(bryophytes) plants N
onvascular
Plants
Liverworts
Origin of plants ANCESTRAL GREEN ALGA
Mosses
Hornworts
plants vascular Seedless
Vascular plants
Lycophytes
Origin of vascular plants Ferns, etc.
Gymnosperms Origin of seed plants
Angiosperms
500
Seed plants
450 400 350 300 50 0 Millions of years ago (mya)
1
2
3
Vascular systems permitted evolution of new specialized plant organs
Roots
Leaves
Lycophytes
Ferns
Horsetails
Three main groups: The Geologic Timetable
<Carboniferous
Seedless Vascular Plants became dominant in the Carboniferous period, about 350 mya
6/25/19
5
Early vascular plant forest, carboniferous period (300 million years ago) Carboniferous
Figure 29.15
Horsetail Fern
Vascular Plants
The Lycophytes: spore-dispersed plants with microphylls
Lycophytes Ferns etc Seed Plants
microphylls
Here are two Lycophytes you can find in Vermont
Ground cedar Shining clubmoss
Lepidodendron - the scale tree of the Carboniferous coal swamp
The remains of the Carboniferous scale trees form the great coal deposits of the world
6/25/19
6
Vascular Plants
The Ferns and friends: spore-dispersed plants with true leaves (megaphylls)
megaphylls
Lycophytes Ferns etc Seed Plants Figure 21.10 Evolution of Leaves
Ferns - the second-most diverse group of vascular plants
ca. 12,500 species
Homospory and Heterospory
Clumps of sporangia (sori) on the underside of a fern leaf
Fig. 29-13-3
Key
Haploid (n) Diploid (2n)
MEIOSIS Spore dispersal
Sporangium
Sporangium Mature sporophyte (2n)
Sorus
Fiddlehead
Spore (n)
Young gametophyte
Mature gametophyte (n) Archegonium
Egg
Antheridium
Sperm
FERTILIZATION New sporophyte
Gametophyte
Zygote (2n)
6/25/19
7
Bryophyte Pteridophytes Gymnosperm Angiosperm
All land plants alternate generations, although the gametophyte became less and less prominent
Fern gametophyte with new sporophyte
ca. 5 mm
Horsetails
Scouring rush
Field horsetail
Moss
Fern
The green part of the moss is _______ and the green part of the fern is ________.
A. Haploid; Haploid B. Haploid; Diploid C. Diploid; Haploid D. Diploid; Diploid E. I don’t know
The Geologic Timetable
<Permian Climate was warming and drying … not a great time to be a spore-dispersed plant!
Vascular Plants
Clubmosses and friends
Ferns and Friends
Seed Plants
megaphylls
seeds
6/25/19
8
Jurassic