Download Chapter 21 Seedless Plants Major modern plant groups All groups

Chapter 21
Seedless Plants
Major modern plant groups
All groups of land-adapted plants have a common
set of characteristics:
All groups of land-adapted plants have a common
set of characteristics:
DNA, fossils, and other characteristics have been
used to construct plant phylogenies.
Plant phylogeny indicates:
Land-adapted plants form a
monophyletic group
Bryophytes
– the first Land Plants
Bryophytes
Based on the appearance of fossil bryophytes,
Bryophytes are rather simple organisms, but
they are found in a wide variety of habitats and
are highly diverse, with over 25,000 described
species.
Bryophytes are very important in many ecosystems.
Bryophytes have a number of features that are similar to their charophyte ancestors, but they also
possess several features that are clearly important for life on dry land.
Bryophyte features shared with charophytes:
Chara
Key innovations that first appeared in bryophytes.
The bryophytes are the first plants with embryos.
In bryophytes, the embryos are immature sporophytes
that are embedded in the tissue of the multicellular
gametophyte.
Mnium
This arrangement of the sporophyte growing from within the
gametophyte provides
Key innovations that first appeared in bryophytes.
2. Gametophyte evolution
Multicellular structures surround the
gametes. These structures are called
gametangia.
3. Stomata and cuticle
Structure of an angiosperm leaf
Stoma, with guard cells
Key innovations that first appeared in bryophytes.
3. Stomata and cuticle
Structure of an angiosperm leaf
The waxy cuticle also helps prevent water loss.
Cuticle on outside of
epidermal cells
Bryophytes comprise three distinct lineages of
plants that do not have lignified vascular tissue.
Hornworts – Phylum Anthocerotophyta
Cells have a single large chloroplast with pyrenoids; they
are the only land plants with this otherwise exclusively
algal characteristic.
Hornworts – Phylum Anthocerotophyta
Liverworts – Phylum Marchantiophyta
Grow primarily in moist, shady areas.
Two different types:
Thalloid liverworts
Leafy liverworts
Liverworts – Phylum Marchantiophyta
The thalloid genus Marchantia
Marchantia reproduces the
gametophyte generation asexually
through the production of small
vegetative structures called gemmae,
which are produced in gemmae cups.
Marchantia also reproduces sexually.
Leafy liverworts
Leafy liverworts are similar in
appearance to mosses, but the leaves
of liverworts have two or three distinct
rows, instead of the spiral arrangement
of leaves on most mosses.
Leafy liverworts
Mosses – Division Bryophyta
Mosses. Vegetative Structure
The first vegetative stage of the gametophyte is the protonema. This
stage looks very much like a filamentous green alga.
The stems of mosses have specialized tissues:
Central Strand
Cell types present in some mosses include hydroids,
which conduct water upward.
The leaves of mosses are not leaves in the true sense of the word.
They do not have conductive tissues that are present in the leaves of
vascular plants.
Mosses – Life Cycle
Haploid spores are produced and released from the
capsule.
The spores germinate into haploid male and female
gametophytes
The moss that you most commonly see is a
combination of the leafy gametophyte and
the sporophyte that does not have leaves.
The capsule, the region of the
sporophyte where the spores are
produced, is often covered by the
calyptra. The capsule may also have
an operculum. These features differ
greatly among the various families of
mosses.
Mosses- Peristome teeth
The capsule opening of many
mosses has a particular
structure called perostome
teeth.
When the moss is moist, the
perostome teeth are incurved.
Longitudinal section through a moss capsule showing all the features.
Study outline-Chapter 21-Bryophytes
-What are the common set of characteristics that all groups of land-adapted plants share?
-Understand how DNA, fossils, and other characteristics have been used to construct phylogenies.
-Understand that charophycean algae are modern protists most closely related to land plants.
-Understand the general characteristics of bryophytes-hornworts, liverworts, and moss
-How are bryophytes important in many ecosystems?
-Understand the number of features that are similar between bryophytes and charophycean algae for life on land.
-What are the key innovations that appeared in bryophytes for life on land?
-Know the three distinct lineages of bryophyteshornworts-Phylum Anthocerotophyta
liverworts-Phylum Marchantiophyta
moss- Phylum Bryophyta
-Know general characteristics of hornworts
-Know general characteristics of thalloid and leafy liverworts
-Know terms-thalloid, rhizoids, pore and air chamber, gemmae, gemmae cups, antheridiophore, archegoniophore
leafy liverwort-archegoniophore, antheridium, gametophyte, sporophyte
-Know general characteristics of mosses
-Know general moss life cycle (Fig. 21.12)
-Know structure of stem-like and leaf-like structures in moss
-Know terms-cortex, central strand, hydroids, leptoids
-Know moss sporophyte structures-Know terms-capsule, operculum, seta (stalk), calyptra, peristome teeth, columnella, spores.