Leaf and Tree a Science Olympiad Event

Report
Leaf and Tree
A
Science Olympiad
Event
If there are
 North America: > 700 different
types
 In the world: > 100,000 type of
trees
How are we going to identify them?
Ideas?
Dichotomous Key

A scientific tool that allows us to
identity something in the natural
world:
 trees,
 wildflowers,
 mammals,
 reptiles,
 rocks,
 fish.
The key consist of a series of choices that you make.
Each choice leads you closer to the correct name of a your item.
Dichotomous means divided into two parts. Therefore, a dichotomous
keys always give two choices in each step.
http://oregonstate.edu/trees/dichotomous_key/index.html
When you look at a dichotomous key it will begin to ask you
questions:
leaf, needle, or scale like
shape of the leaves
needle count
pine cones
how needles are clustered
Okay so what are all the things we need to have before we can
identify a tree?
Leaf, picture of tree for height, bark, entire branch with older
leaves (not just tip of the branch where new leaves/needles are
located), sample of fruits or cones.
A Walk in the Park

http://nationalzoo.si.edu/Education/Conservati
onCentral/walk/default.cfm
Winter


No leaves on the tree!!
What are you going to do?

Look on the ground beneath
the tree for shed leaves and
seeds can often help. Be
careful of mixing up the
leaves between neighboring
trees though.

leaves have fallen, look down

There are buds and twigs high
in the tree but out of reach


Narrow down by location TN vs GA
vs WA – use a field guide specific to
your area
bark design can give you clues
Summer

Much easier than Winter time!
Leaves and needles give us a lot
of information.

Bark

Seeds, acorns

Location



Okay so when you begin lab
there are many questions you
will need to answer.
You will have a station with a
web page, or a field guide in
either book format or printed
handout.
Questions you will be looking to
answer:
Needles or Leaves

1. Opposite growth
pattern −


Twigs and/or leaves
are attached to the
limb directly across
from one another.
2. Alternate growth
pattern −

twigs and/or leaves
are attached to the
limb in a zigzag
pattern not across
from one another.

3. Simple leaf −


A leaf that has only one leaflet attached to the
tree limb.
4. Compound leaf −

A leaf that has two or more leaflets attached to a
central leaf stem that is in turn attached to the
tree limb.

5. Margins of the
leaves:



Bristle tip − projects
out from the central
leaf like a finger on a
hand.
Needle-like point
sticking out at the
end of each lobe.
Toothed margin −
Coarse to finetoothed edges.
1. Are the trees EVERGREEN
with needles arranged in
clusters of 2-5?
2. Are the trees EVERGREEN
with needles arranged
singly?
3. Are the trees DECIDUOUS
(shedding all leaves
annually) with needles
arranged in clusters of
many on short, spur-like
branches?
4. Are the trees DECIDUOUS
with needles of uneven
length flattened along the
twig. The cone a 1"
diameter green or brown
wrinkled ball?
Needle Like or
Scale Like
Types of Fruits and
Cones (book)
Types of Silhouettes

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