Field and 150 Student Background Handout Pilot 2
Early Land Plants Today
Contributing Data to an International Project Documenting Biodiversity
Current data suggests that extinction rates are at extremely high levels and many scientists feel
that we may currently be in what would be the sixth mass extinction period of the last 540 million
years (Barnosky et al., 2011). In an effort to preserve and protect some of our most vulnerable
species, the Field Museum in conjunction with the Encyclopedia of Life has set out to collect and
categorize our planets’ remaining biodiversity. As you might imagine, this is a massive
undertaking and we need your help. The data you collect today will be used by an international
group of scientists to analyze, catalog, and discover new species. You are one of the first groups of
any kind to participate in such a massive undertaking and collaboration. Please pay particular
attention to detail when collecting and analyzing your data. This is not, “just another assignment.”
Your time and efforts are appreciated. Thank you.
Generally speaking, all living things can
be classified into one of three distinct
kingdoms- Plants, Animals, and Protists.
Today, we will be working in the Plant
Kingdom. Kingdom Plantae can be
further broken down by the type of
vascular tissue as seen by the simple
cladogram to the left. Today, we are
interested in investigating the
Liverworts. Liverworts are a group of
early land plants that we do not know
much about- only recently have their
environmental and potentially lifesaving roles been established.
What’s a Liverwort? All land plants are classified into one of two groups. Vascular land plants,
characterized by the compound lignin, contain special water transport cells that give them the
ability to grow to great heights and in arid environments. Non-vascular land plants, on the other
hand, are typically found in wet areas and are much smaller. Non-vascular land plants are called
Bryophytes and can be further classified as Mosses, Hornworts, or Liverworts. Did you know that
every Bryophyte spends most of its life as a haploid organism? These special organisms can be
found all over the world from Fiji to Alaska. There might even be some in your backyard! With so
many different organisms, scientists need your help to learn about each one. Your participation in
the project will help groups of scientists learn more about each of these species and the
differences between them. Who knows what we will discover?!
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Field and 150 Student Background Handout Pilot 2
Why Liverworts? Bryophytes play a major ecological role. The small size of these organisms
enables them to respond rapidly to environmental and ecological change offering them great
utility in conservation science. They have been used as indicators of past climate change and as
early indicators of global warming. A growing body of evidence also identifies liverworts as the
earliest diverging lineage of bryophytes, so they are considered evolutionary very significant.
Chemical compounds extracted from liverworts also exhibit important biological activity. For
example, chemical extracts derived from Frullania species have been found to have cytotoxicity
against certain cancer cell lines, and significant antimicrobial and antifungal activity.
The particular group of Liverworts that you are going to be working with today is from the genus,
Frullania. These organisms have many unique adaptations and features that become visible only
under high power magnification. Today’s investigation will concentrate on their morphological
characteristics. Taxonomists use these characters to distinguish amongst the different species of
plants. Today, you might be the first person to analyze or describe a particular feature. You might
be the one to discover a new species!
Accelerating biodiversity discovery — Plant systematists (scientists who study
diversification of plants, including evolutionary relationships) attempt to provide multiple
lines of independent evidence when testing hypotheses and describing new species.
Scientists are investigating a potential new species to science, which is included in the
laboratory that you will be participating in. Genetic evidence is presented in a paper
published earlier this year. ( http://www.pensoft.net/journals/phytokeys/article/2496 )
Scientists are now investigating morphological evidence. The images you are investigating
today are from collections based at The Field Museum and are an indispensible resource to
investigate species relationships, distribution patterns, and diversity.
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Field and 150 Student Background Handout Pilot 2
A
Matter of SCALE !
Sometimes the plants and animals we see with the naked eye don’t look that impressive, but we
often find that when we take a more careful look many secrets are revealed. Frullania, which has
been described as “dried worms” comes alive under the microscope! When you look at the
images, keep in mind the general biological size references below. It’s all a matter of scale.
Anatomy 101
To familiarize ourselves with the images, let’s investigate the basic structures we will be working
with today.
The image on the left shows us several important features of Frullania cells, while the image on
the right shows us how to measure them.
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Field and 150 Student Background Handout Pilot 2
Cells walls- used for structure and communication
Cell lumina- holds the inner contents of the cells
Trigones- thickenings where three cell walls meet.
When we measure a cell, we want to measure the entire cell, including both the lumen and the
cell wall. Sometimes it can be difficult to determine where one cell’s wall ends and another starts.
To get around this, we measure from one edge of the lumen to the outer edge of the next cells
lumen as shown above. This way, we account for the depth of the cell wall.
Zooming out from the leaf cell margin, we can begin to see the structure of the whole plant and its
form takes shape!
Sources
Nature 471, 51–57 (03 March 2011)
http://www.pensoft.net/journals/phytokeys/article/2496
The Field Museum, Dept. of Botany
REGISTER NOW – Email [email protected]
You will receive periodical updates on the status of your data and a forthcoming
website that is currently under development.
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