Navigation
Return to
Table of
Content

Return to
Biology 2108
Dr. D.'s
Home
Page
KSU Home
Biology 2108 Lecture
Biodiversity: Plants

 

bryophytes
PLANTS

pteridophytes



seed plants


What makes a plant a plant?
Multicellularity, chorophyll a & b, and cellulose cell walls are all characteristics scattered among several algal groups (i.e. photosynthetic protists).  So, are these alone good chararteristics to distinguish plants from protists?

However, other characteristics distinguish plants from algae:



How is this different from the life cycle of animals?

Some systematist feel that there should be a broader definition of (wider inclusion for) the Kingdom Plantae to include certain groups of green and red algae to form a monophyletic group with plants (i.e. the Archaeplastida).  In any case, the group of terrestrial plants defined by the above characteristics appears to be a monophyletic group in itself.


From what organisms did plants evolve?

Charophyceans,
a group of multicellular green algae that inhabit shallow waters on ponds and lakes, appear to be most closely related to plants based on:
Is it correct to say then that modern plants evolved from charophyceans?

Evidence of plants appears in the fossil record over 500 million years ago.




Group
Major phyla
Characteristics
Examples


Non-vascular plants

(Bryophytes)
lack structural specialization
related to photosynthesis and
acquisition of nutrients. 
Gametophyte stage predominates
Phylum Hepatophyta
often flatten form
with leaf-like structure
liverworts


Phylum Bryophyta


usually erect form with
fine leaf-like structures
that are one cell layer thick
mosses





Vascular seedless plants
vascular tissue for transport,
but lack protective seed.

Phylum Lycophyta
microphyll leaves
club mosses, spike mosses, quillworts

Phylum Pterophyta megaphyll leaves (as do
vascular seed plants)

ferns, horsetails






Vascular seed plants

vascular tissue for transport,
protective seed.
Sporophyte stage predominates

Phylum Coniferophyta
  
A gymnosperm (ovules and seeds develop on the surfaces of specialized leaves and also includes ginkos and cycads).  Conifers bear cones.
Pines and other evergreen trees
Phylum Anthophyta
  • Monocots
  • Eudicots


An angiosperm (seeds enclosed in ovary which matures into a fruit).  Why should a plant produce fruit? flowering plants
         




Major trends in plant evolution appears to have been driven mainly by selection pressures related to adapting to a terrestrial environment.  Other pressures (i.e. competition for sunlight, and herbivores and pathogens) were likely less important as plants first colonized the land.

It has been suggested that the multicellular sporophyte stage evolved as a way to produce more offspring to maximize sexual reproduction in a terrestrial environment where a shortage of water would decrease the probability the swimming sperm would fertilize eggs.

  Non-vascular plants
includes liverworts, hornworts, and mosses

Bryophytes include the characteristics listed above that distinguish plants from other groups.

However, bryophytes lack structural specialization related to photosynthesis and acquisition of nutrients that is characteristic of other plants.  How would the location of resources (light, water, and nutrients) needed by plants differ in aquatic versus terrestrial environments?  
Bryophytes reach on a maximum height of a few centimeters.  Given the answer to the question, above, what adaptation would be necessary for plants to achieve greater size?

 
  Vascular plants

Seedless plants
includes lycophytes, ferns, horsetails

The flagellated sperm of non-seed plants requires what type of environmental conditions for reproduction?


Seed plants

What's so important about the endosperm (the seed's "food supply") to humans?






bryophytes
PLANTS

pteridophytes



gymnosperms




angiosperms

 Back to the Tree of Life

Navigation
Return to
Table of
Content

Return to
Biology 2108
Dr. D.'s
Home
Page
KSU Home