Slowly but surely, according to Journey North classrooms, the leaves are beginning to emerge in a few places. We hope you're prepared to report leaf-out on your adopted tree. When its leaves are the size of a U.S. quarter, please send a report to Journey North. Simply fill out a Field Data Form by selecting the blue button below labeled, "Report Field Observations".
How do Trees Know its Spring?
Have you ever wondered how trees know when it's time for their leaves to grow? Do warm temperatures ever trick trees into producing leaves early? After all, a week of warm weather in the middle of winter can seem like spring. Imagine what would happen if a tree confused January with June! Consider what you've learned about timing in nature and see if you can answer this Challenge Question.
Challenge Question #49
"How do trees 'tell time'?"
To respond to this Challenge Question please follow the instructions at the end of this report.
Leaves in the Deep Freeze
Try This: Put a leaf of lettuce in the freezer. While it's there, discuss how you expect it to look when you take it out. After about an hour, take the leaf out of the freezer and inspect it. What happened? If you could look at the cells of the leaf under a microscope, what would you expect to see? Why? You're welcome to write up your observations and share them with us! Send them by e- mail to: jnorth@learner.org
Temperature and Leaf-Out
Thanks to students in California, Maine and the Marshall Islands for their answers to Challenge Question # 28: "According to the Growing Degree Day equation, at what minimum temperature do leaves on deciduous grow?" You'll find their comments below.
Leaf -Out Observations Through March 22, 1996
Date............Place...............(Comments)
03/08/96........Redding, CA..........("Willows leafed out")
03/11/96........Kent, Washington.....(" Have quarter sized leaf out")
03/12/96........Whitesboro, New York.("Pussywillows")
03/15/96........Oley, PA.............("Only has buds")
From CALIFORNIA:
March 8, 1996
Willows leafed out MAR 8, but oak trees are many weeks away.
Triston Mosbacher and Zephyr Krafel
Chrysalis School
Paul Krapfel Carter House Natural Science Museum
carterhouse@shastalink.k12.ca.us
From WASHINGTON:
March 11, 1996
Sighted the first robin and also have quarter sized leaf out on Japanese flowering cherry trees and maple trees. All other trees have buds just emerging. Average daily temperature for last week has been between 43-50. Its really warming up.
Wesley Harness
Grass Lake Elementary
wharness@kent.wednet.edu
From NEW YORK:
March 12, 1996
This is Courtney Robinson, from Whitesboro Middle School, Whitesboro, New York. We are in central New York, near Utica. We don't have any leaves out yet but we do have some pussywillows. The tree is in my side yard and the buds first opened on Tuesday, March 12, 1996. Only the buds on the top of the tree have started to open, the buds on the bottom are still closed. I was wondering if there are any other pussywillows opening.
From PENNSYLVANIA:
March 15, 1996
The tree we adopted only has buds. The buds are still very tight with no green color showing. The weeping willows have a yellow color to their branches and are easy to spot along the road.
Mrs. Cheryl Moretz
Oley Valley Elementary School
leckert@fast.net
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Students' Responses to Challenge Question # 28:
From MAINE:
I think the leafs will start growing when the temp. is 41 because if you - 40 you will get more that 0, and that would start the growing days.
Nisse Greenberg, Gr. 4 Conners School
mhg4@emerson.u98.k12.me.us
From the MARSHALL ISLANDS:
40 degrees is the minimum low temperature for deciduous trees to grow leaves.
Matt Knutson George Seitz Elementary School
APO AP popejoy@ALOHA.NET
From CALIFORNIA:
Leaf-Out starts at 45 F
LPMiddle@aol.com
How to Respond to Challenge Question # 49:
1. Address an e-mail message to: jn-challenge@learner.org
2. In the Subject Line of your message write: Challenge Question # 49.
3. In the Body of your message answer this question:
"How do trees 'tell time'?"
The Next Leaf-Out Update Will be Posted on April 5, 1996
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