The Plant
Kingdom
• Origins 500- 475
MYA
• 10 Phyla
• 4 Basic lifecycles
• Green algae that
evolved onto land
• Evolved becoming
more terrestrial,
independent from
water
• Then coevolved with
pollinators, dispersal
Tentative
Phylogeny
Fig 28.8
An overview of land plant evolution
Land plants
Vascular plants
Figure 29.7
Angiosperms
Origin of seed plants
(about 360 mya)
Origin of vascular
plants (about 420 mya)
Origin of land plants
(about 475 mya)
Ancestral
green alga
Seed plants
Gymnosperms
Pterophyte
(ferns, horsetails, whisk fern)
Seedless vascular plants
Lycophytes
(club mosses, spike mosses, quillworts)
Mosses
Hornworts
Liverworts
Charophyceans
Bryophytes
(nonvascular plants)
Lab
• Chara Lifecycle
• Moss Lifecycle
– Liverworts
• Fern Lifecycle
– Lycophytes
Charophyceans- plant’s green algae
ancestor
Chara - 30
Coleochaete- 31
Modern examples of charophyceans
Chara sp. (green algae)
Chara Slide #30
Oogonia
Antheridia
Chara sp.
Oogonia
Antheridia
Alternation of Generations
• Separate multicellular haploid and diploid
phases
– (2n) Sporophyte make spores by meiosis
– (n) Gametophyte makes gametes by mitosis
• Sperm and egg (moss & fern)
• Pollen and Ovule (gymnosperm & angiosperm)
• The sporophyte and gametophyte are very
different in morphology
– Vascular tissues only appear in sporophyte phase
• Sporophyte becomes more dominant in new
plant groups
• Charophyceans lack sporophyte phase
Characteristics that Plants share
with the green algae group
Charophyceans
• Autotrophic Multicellular Eukaryote
• Have cell walls made of cellulose
– Made by rosette cellulose-synthesizing
complexes
– 20-26% of wall material, closest match in algae
• Chloroplast similarities
– have chlorophyll a & b, use β-carotene as
accessory
– Thylakoids stacked in grana
– Chloroplast DNA comparisons
Characteristics that Plants share
with the green algae group
Charophyceans
• Peroxisome enzymes
• Cell plate formation by phragmoplast
• Nuclear membrane breaks down during
mitosis
• Sperm ultrastructure - biflagellate
• Gene sequences – rRNA, Cytoskeleton
proteins
Switch to sporophyte
dominance
What’s new in Mosses?
( Derived Traits)
•
•
•
•
•
Spores / sporangia
Sporophyte phase
Upright growth on land
Cuticle
Multicellular gametangia
The Bryophytes
• Bryophytes are represented by three phyla:
– Division Hepatophyta - liverworts
– Division Anthocerophyta - hornworts
– Division Bryophyta – mosses
Liverworts and hornworts
are believed to be more
similar to what early
plants were like.
Bryophyte lifecycle: moss
• Haploid dominant
• No vascular tissues
• Filamentous
protonema stage
• Swimming sperm
• Disperse by spores
• Dependent
sporophyte
• Dioecious
gametophytes
• No true leaves
• Rhizoids, not roots
Pteridophytes evolved over 400 MYA
Seedless, Vascular plants (having Xylem &
Phloem). Today represented by two phyla:
Pterophyta: Ferns, Horsetails (Equisetum)
Lycophyta: Club moss
Cooksonia, an extinct plant
over 400 million years old, is
the earliest known vascular
plant.
Protonema
Protonema - #32
Moss
Antheridia
Antheridia on stalk
Moss Antheridia # 33
Moss Archegonia
Moss Archegonia #34
Moss Archegonia #34
Moss
Sporangia
Moss Sporangia- 35
Moss Sporangia- # 35
An overview of land plant evolution
Land plants
Vascular plants
Figure 29.7
Angiosperms
Origin of seed plants
(about 360 mya)
Origin of vascular
plants (about 420 mya)
Origin of land plants
(about 475 mya)
Ancestral
green alga
Seed plants
Gymnosperms
Pterophyte
(ferns, horsetails, whisk fern)
Seedless vascular plants
Lycophytes
(club mosses, spike mosses, quillworts)
Mosses
Hornworts
Liverworts
Charophyceans
Bryophytes
(nonvascular plants)
WALLED SPORES PRODUCED IN SPORANGIA
Spores
Sporangium
Longitudinal section of
Sphagnum sporangium (LM)
Sporophyte
Gametophyte
Sporophyte and sporangium
of Sphagnum (a moss)
MULTICELLULAR GAMETANGIA
Female gametophyte
Archegonium
with egg
Antheridium
with sperm
Archegonia and antheridia of
Marchantia (a liverwort)
Male
gametophyte
MULTICELLULAR, DEPENDENT EMBRYOS
Embryo
Maternal tissue
2 µm
Embryo and placental transfer
cell of Marchantia
10 µm
Wall ingrowths
Placental transfer cell
Liverwort Gametophyte
Female Gametophyte
Liverwort Antheridia
• Antheridia are on the upper surface of the
“umbrellas”
Liverwort Antheridia
Liverwort Archegonia
• Archegonia are on the undersides of the
“umbrellas”
Liverwort Archegonia
Liverwort Archegonia - egg
Liverwort Sporangia
• On undersides- develop from archegonia
Gemmae & cups
Gemmae & cup
An overview of land plant evolution
Land plants
Vascular plants
Figure 29.7
Angiosperms
Origin of seed plants
(about 360 mya)
Origin of vascular
plants (about 420 mya)
Origin of land plants
(about 475 mya)
Ancestral
green alga
Seed plants
Gymnosperms
Pterophyte
(ferns, horsetails, whisk fern)
Seedless vascular plants
Lycophytes
(club mosses, spike mosses, quillworts)
Mosses
Hornworts
Liverworts
Charophyceans
Bryophytes
(nonvascular plants)
Vascular tissue
• Allows plants to grow taller
• More support by lignified xylem tracheids
• Can pull water up from soil
– Can tolerate soil that is drier on the surface
• Form parts of true leaves and roots.
• Only found in diploid tissue
– Lead to sporophyte dominance?
Fern Lifecycle
• Diploid dominate
• Gametophyte still independent, short
lived,
– monoecious in fern (Pteridophyta)
– dioecious in club “moss” (Lycophyta)
• Spores disperse plant
• Sporophyte perennial
Pteridophytes evolved over 400 MYA
Seedless, Vascular plants (having Xylem &
Phloem). Today represented by two
divisions:
Pterophyta: Ferns, Horsetails (Equisetum)
Lycophyta: Club moss
Cooksonia, an extinct plant
over 400 million years old,
is the earliest known
vascular plant.
LYCOPHYTES (PHYLUM LYCOPHYTA)
Strobili
(clusters of
sporophylls)
Isoetes
gunnii,
a quillwort
Selaginella apoda,
a spike moss
Diphasiastrum tristachyum, a club moss
Psilotum
nudum,
a whisk
fern
PTEROPHYTES (PHYLUM PTEROPHYTA)
Equisetum
arvense,
field
horsetail
Vegetative stem
Athyrium
filix-femina,
lady fern
Strobilus on
fertile stem
WHISK FERNS AND RELATIVES
HORSETAILS
FERNS
Carboniferous forest based on
fossil evidence
Fern Gametophyte # 37
Fern Gametophyte # 37
Young Sporophyte
#38
Vascular tissues in young frond
Fern Antheridia
Fern Arcghegonia
Fern Sporangia
- Sori
Annulus
Sporangium
# 40
Indusium
Whisk Ferns
(formerly separate phylum: Psilophyta)
Figure 29.13 Hypotheses for the
evolution of leaves
Vascular tissue
(a) Microphylls, such as those of lycophytes, may have
originated as small stem outgrowths supported by
single, unbranched strands of vascular tissue.
(b) Megaphylls, which have branched vascular
systems, may have evolved by the fusion of
branched stems.
Horsetails – Equisetum sp.
(formerly separate phylum: Sphenophyta)
LYCOPHYTES (PHYLUM LYCOPHYTA)
Strobili
(clusters of
sporophylls)
Isoetes
gunnii,
a quillwort
Selaginella apoda,
a spike moss
Diphasiastrum tristachyum, a club moss
Psilotum
nudum,
a whisk
fern
PTEROPHYTES (PHYLUM PTEROPHYTA)
Equisetum
arvense,
field
horsetail
Vegetative stem
Athyrium
filix-femina,
lady fern
Strobilus on
fertile stem
WHISK FERNS AND RELATIVES
HORSETAILS
FERNS
Lycophyta
Club “Moss”
Strobilus
• Not a moss !!! ( a common name)
• Heterosporous
– Meagsporania & Microsporangium
– Form Strobili (cones)
Selaginella – strobilus Microsporangium
#41
Megasporangium
4 megaspores
Many microspores
Megaspore gametophyte
Switch to sporophyte
dominance