Chapter 29-Plant Diversity I: How Plants
Colonized Land
Plants inhabit all but the harshest environments
Plants enabled other life-forms to survive on land
For example, plants supply oxygen and are a key source of food for terrestrial animals.
Also, by their very presence, plants such as the trees of a forest physically create the
habitats required by animals and many other organisms
Concept 29.1: Plants evolved from green algae
charophytes are the closest relatives of plants.
plants are multicellular, eukaryotic, photosynthetic autotrophs,
o as are brown, red, and certain green algae
Plants have cell walls made of cellulose
o So do green algae, dinoflagellates, and brown algae
chloroplasts with chlorophylls a and b are present in green algae, euglenids, and a few
dinoflagellates, as well as in plants
the charophytes are the only present-day algae that share the following distinctive traits
with plants, suggesting that they are the closest living relatives of plants:
o Rings of cellulose-synthesizing proteins
The cells of both plants and charophytes have distinctive circular rings of
proteins embedded in the plasma membrane.These protein rings
synthesize the cellulose microfibrils of the cell wall. In contrast, non-
charophyte algae have linear sets of proteins that synthesize cellulose
o Structure of flagellated sperm
In species of plants that have flagellated sperm, the structure of the sperm
closely resembles that of charophyte sperm
o Formation of a phragmoplast
a group of microtubules known as the phragmoplast forms between the
daughter nuclei of a dividing cell.A cell plate then develops in the middle
of the phragmoplast, across the midline of the dividing cell. The cell plate,
in turn, gives rise to a new cross wall that separates the daughter cells
o Cuticle
(1)A waxy covering on the surface of stems and leaves that prevents
desiccation in terrestrial plants. (2) A tough coat that covers the body of a
nematode.
o Stomata
A microscopic pore surrounded by guard cells in the epidermis of leaves
and stems that allows gas exchange between the environment and the
interior of the plant.
Although this evidence shows that plants arose from within a group of charophyte algae,
it does not mean that plants are descended from these living algae
Sporopollenin
o a layer of a durable polymer that prevents exposed zygotes from drying out
,
Give such traits that are found in plants but not in charophyte algae:
o Alternation of generations, multicellular(dependent embryos),walled spores
produced in sporangia, multicellular gametangia, Apical meristems
Colonized Land
Plants inhabit all but the harshest environments
Plants enabled other life-forms to survive on land
For example, plants supply oxygen and are a key source of food for terrestrial animals.
Also, by their very presence, plants such as the trees of a forest physically create the
habitats required by animals and many other organisms
Concept 29.1: Plants evolved from green algae
charophytes are the closest relatives of plants.
plants are multicellular, eukaryotic, photosynthetic autotrophs,
o as are brown, red, and certain green algae
Plants have cell walls made of cellulose
o So do green algae, dinoflagellates, and brown algae
chloroplasts with chlorophylls a and b are present in green algae, euglenids, and a few
dinoflagellates, as well as in plants
the charophytes are the only present-day algae that share the following distinctive traits
with plants, suggesting that they are the closest living relatives of plants:
o Rings of cellulose-synthesizing proteins
The cells of both plants and charophytes have distinctive circular rings of
proteins embedded in the plasma membrane.These protein rings
synthesize the cellulose microfibrils of the cell wall. In contrast, non-
charophyte algae have linear sets of proteins that synthesize cellulose
o Structure of flagellated sperm
In species of plants that have flagellated sperm, the structure of the sperm
closely resembles that of charophyte sperm
o Formation of a phragmoplast
a group of microtubules known as the phragmoplast forms between the
daughter nuclei of a dividing cell.A cell plate then develops in the middle
of the phragmoplast, across the midline of the dividing cell. The cell plate,
in turn, gives rise to a new cross wall that separates the daughter cells
o Cuticle
(1)A waxy covering on the surface of stems and leaves that prevents
desiccation in terrestrial plants. (2) A tough coat that covers the body of a
nematode.
o Stomata
A microscopic pore surrounded by guard cells in the epidermis of leaves
and stems that allows gas exchange between the environment and the
interior of the plant.
Although this evidence shows that plants arose from within a group of charophyte algae,
it does not mean that plants are descended from these living algae
Sporopollenin
o a layer of a durable polymer that prevents exposed zygotes from drying out
,
Give such traits that are found in plants but not in charophyte algae:
o Alternation of generations, multicellular(dependent embryos),walled spores
produced in sporangia, multicellular gametangia, Apical meristems
