Example report by Tim Reluga for Laboratory 1
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For my report, I am going to discuss trees, and how we identify and compare
them.  In particular, I would like to start with a subset of trees called
conifers.

Because we have to start someplace, let's assume that we are all able to
recognize a tree, which is a plant taller than an adult person, with roots, a
trunk, branches, and leaves.  A conifer is a special kind of tree.  The most
easily observed characteristics of conifers are as follows.  (1)  The leaves of
a conifer are long and narrow.  They are usually referred to as needles because
there shape resembles that of a needle.  (2) Conifers keep their needles all
year round, unlike many other trees which lose their leaves in winter and
regrow them in spring.  Conifers are often called "evergreens" because they
keep their needles in winter.  A related characteristic is (3) that conifers
usually live in temperate or cold climates where there is snow and limited
sunlight for atleast part of the year. (4)  Conifers reproduce by growing
recognizable organs called "cones".  Cones are egg-shaped structures that grow
on branches.  The consist of many petals of bark distributed radially around a
central stem, and are usually brown or green.  Male cones contain pollen, and
female cones contain seeds.  Two of these characteristics can be identified
visually, at most times.  The other two are visual also, but require comparison
with particular environmental contexts, such as if it is winter, which can
employ other senses as well.

One of the most common examples of a conifer is a white pine tree.  White pine
trees meet all three of these conditions.  They have long, narrow needles that
stay on the tree all year round, they live in the northern US and Canada, as
well as at high elevations, and they produce pine cones.  However, not all
conifers satisfy all four of these characteristics.  For instance, larch trees
lose their needles every winter and regrow them in the spring.  Yew trees have
berry-like red fruits instead of cones, while juniper trees have blue berries.
Redwoods have short, scaly leaves.  And some conifers like bristle-cone pines
prefer hot, dry climates.

Why do we count these exceptions as conifers even though they don't have all
the common characteristics?   Because the weight of these and other
less-obvious characteristics indicates that these exceptional examples are
still more-closely related to each other than to any other group of trees.  The
strongest evidence today is provided by DNA sequencing.  Although DNA can not
be seen with the naked eye, it has proven to be a highly reliable source of
information in establishing evolutionary relationships among individuals and
species.  DNA evidence confirms that these conifers all possess a most-recent
common ancestor that was very different from the most recent common ancestor of
other tree species.

Trees within the conifer species can be sub-divided based on several other
characteristics. ... < and so on until the topic is exhausted >