Download Lab_09_PlantDiversity_Scavenger Hunt

Biol 160: Lab 9
Name: __________________________
Exploring Plant Diversity
OBJECTIVES
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Become familiar with the diversity of plants.
Understand how each group of plants is defined by one or more evolved traits.
General Procedures
Read the following information to help you understand the nature of plant diversity. Go on a
self-guided scavenger hunt, around your neighborhood, to a local park, or out to the wilderness
and observe the diversity of plants!
Plant Diversity Scavenger Hunt and Comparison of Plant Diversity
The assignment - Plant diversity scavenger hunt!
Part I: “Collecting”: In order to help you become more familiar with common members of the
major plant groups you will be taking pictures of specimens from each plant group. While
“collecting” your pictures, pay attention to the overall size of the plants you are collecting from,
and in what environment type you found them. Take a picture (or just collect it if you don’t
have a camera) of one specimen from each of the following groups:
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Bryophytes or non-vascular plants (mosses)
Seedless vascular plants (ferns and horsetail)
Gymnosperms (conifers or cone-bearing trees)
Angiosperms (flowering plants)
Part II: Researching your specimens: On the computer or through reference books, find out
more about the plants that you found. Include the name of the plant, the major plant group
that it belongs to, where it normally grows (and where you found it), how big the plant grows,
and any other interesting information that you find about it. Make sure you cite your sources.
Are they reliable? Since this is the fall, you may not be able to find awesome specimens of
each type. You can go to grocery and plant stores if you can’t find anything around town and
just take a picture of it.
Information to help you in your search:
A) Nonvascular plants “Bryophytes” (mosses)
The Bryophytes, or nonvascular plants, represent the earliest group of
terrestrial plants. The most familiar species in this group are the mosses. They
do not have vascular tissue (some mosses have simple tubular structures).
Vascular tissues serve two main purposes in plants: 1) as a transport system
(tubes) for moving water, sugars and minerals throughout the plant, and 2)
it provides structural support. Because Bryophytes do not have vascular
tissue, they do not have true leaves, stems and roots. The lack of vascular
tissue limits the Bryophytes morphologically and ecologically. Without
vascular tissue to transport water, a Bryophyte must be low lying or mat-like,
so that all of its body can be in contact with the moist environment, and
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Biol 160: Lab 9
also be fairly thin in structure (only a few cells thick). Since water is moving via osmosis through
cells (a relatively slow process), the plant cannot be very thick. Most Bryophytes need to live in
moist environments, although they have many adaptations for living in dryer environments.
Additionally, the lack of vascular tissue means that Bryophytes do not have the structural
support to grow tall. Since the Bryophytes are all fairly short plants, this leads to strong
competition for sunlight and space.
B) Seedless vascular plants (ferns & horsetails)
Vascular tissue is composed of cells joined into tubes transporting
water and nutrients throughout the plant body. Xylem tissue is the
water-transport tissue carrying water and minerals from the roots up
the plant body, and phloem tissue is the food-transport tissue
carrying phloem sap (food nutrients) from food sources (leaves or
food storage organs) to food sinks (growing non-photosynthetic
structures or food storage organs). The bodies of the vascular plants
are divided into an aerial shoot system (stems, leaves, and
reproductive structures), and an underground root system. True
leaves, stems, and roots all contain true vascular transport tissue.
The development of vascular tissue allowed the vascular plants to
grow much taller than the non-vascular plants for two reasons: 1)
plants with vascular tissue no longer had to have most of their body in contact with a moist
environment, and 2) vascular tissue provided structural strength within stems. Growing taller
meant that they could intercept the light before low-growing plants could. This allowed the
seedless vascular plants to become dominant during the Carboniferous period. The most
familiar seedless vascular plants are ferns. Both seedless vascular plants and Bryophytes use
spores to disperse (move the next generation further away from the parent generation). Ferns
have special spore producing structures, called sori, that are typically visible underneath their
leaves, which often look like rows of brown, green or whitish dots.
C) Seed bearing vascular plants: Gymnosperms
Seed bearing vascular plants developed two structures that helped
this group be successful in dryer environments: 1) pollen, and 2) the
seed. These structures are found in both gymnosperms and
angiosperms. Pollen is the male gametophyte (which will produce the
sperm), wrapped in a protective coating. Pollen allowed for the
dispersal of the male gamete (sperm) over longer distances and
without the need for water. In Bryophytes and seedless vascular plants
the sperm must swim to the egg, so they require a moist environment.
In seed bearing vascular plants, the zygote develops into an embryo
within the ovary. The embryo, its food supply and a seed coat are
packaged together by the plant as a seed. The seed can be released
from the plant
to germinate in appropriate environmental conditions. Seeds provide
several reproductive advantages for these plants. First, they can increase dispersal of the next
diploid generation as the seed can be carried by the wind, water, or another organism.
Second, the food supply gives the developing embryo an energy boost early in its life. With this
energy boost, the embryo will produce leaves that allow for photosynthesis and metabolic
independence. Third, the seed coat provides protection for the embryo while it waits to
germinate until conditions are suitable.
The most familiar gymnosperms are members of the conifer, or “cone-bearing”, group
which includes pine, fir, cedar and spruce trees. Gymnosperm means “naked seed”. The seeds
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Biol 160: Lab 9
of gymnosperms are not enclosed. In conifers they develop on the scales of the cone.
Gymnosperms can be quite tall and can be found both in moist and dry environments. Almost
all the conifers are “evergreen”, holding their needle-like or scale-like leaves year round. This
allows for growth year round, although this growth is reduced in the seasons of least sunlight.
The reduced leaves are adapted to colder, drier climates with a thick cuticle (waxy layer that
prevents water loss). Commercially, most of our lumber and paper pulp comes from the wood
of conifers.
D) Seed bearing vascular plants: Angiosperms
The angiosperms are recognized as the “flowering
plants.” In addition to pollen and seeds, the
angiosperms developed two other distinctive traits: 1)
flowers, and 2) fruits. Flowers are made up of four main
parts: 1) sepals, 2) petals, 3) stamen, and 4) carpels.
Many flowers have been modified to attract insect,
bird or mammal pollinators. Modifications include bright
colors, scents or nectar rewards.
Angiosperm means “container seed”, and the
seeds are found within fruit. Fruit is a development of
the ovary tissue that surrounds the seed. Fruit evolved
to aid in dispersal of the seeds.
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