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fall through, to fail to be accomplished.to come out: His hair fell out after a few weeks of chemotherapy.to quarrel ĭisagree: They had fallen out only a week before their wedding.to experience or come upon: Once again we had fallen on bad times.to become the obligation or duty of: The welfare of the family fell on me.to assault: The gang fell on their rivals with knives and chains.fall off, to decrease in number, amount, or intensity ĭiminish: The winds fell off once the storm passed.fall in with, to start to associate with: to fall in with bad company.to fall in love with: He had fallen for her pretty badly.to be deceived by: I can't believe you would fall for an old trick like that.to lag in pace or progress: to fall behind in their studies.Rely on: We had no savings to fall back on. fall back on or upon, to have recourse to.Retreat: The troops fell back to their fortified positions. to slope or extend in a downward direction: The field falls gently to the river.to come by right: The inheritance fell to the only living relative.Īppear disappointed or dismayed: The child's face fell when the bird flew away.to have its proper place: The accent falls on the last syllable.to come to pass or occur at a certain time: Christmas falls on a Monday this year.to come by lot or chance: The chore fell to me.

to come or occur as if by dropping, such as stillness or night: The sun went down and night fell rapidly.to pass into some physical, mental, or emotional condition: to fall into a coma.to be overthrown, such as a government: The dictatorship had finally fallen.to give in and lose to an attack: The city fell to the enemy.to become unchaste: He had fallen into sin. to become lowered or directed downward: Her eyes fell as she began to explain why she had stolen the money.to leave a standing or erect position suddenly: I fell to my knees. to come or drop down suddenly to a lower position, esp.to drop or come down under the force of gravity: The apple fell from the tree.That means more new tree leaves to watch bud in the spring and more leaves to jump in when fall comes around again.Fall /fɔl/ USA pronunciation v., fell /fɛl/ USA pronunciation fall It will help them survive.Īs fallen leaves break down, or decompose, they can also provide some nutrients to the soil and play a part in helping a new generation of trees to grow. For some trees, it’s better just to have bare branches during the cold seasons. Instead of continuing to make leaves that would otherwise just die during a frost, the trees store up some nutrients from their leaves in other parts of the tree before the winter. It’s really valuable, and the plant would rather keep that stuff around,” Adams said. These nutrients include things like magnesium and nitrogen that help the trees grow. Plants put a lot of important stuff called nutrients, which is kind of like their food source, into their leaves. Big flat leaves are a problem if they freeze and die, Adams said. It’s actually a good thing the tree doesn’t want to keep its leaves, though. When the days get shorter and colder as they do during fall in the Northern Hemisphere, that’s a signal to the plant to stop making the leaf-attaching chemical, auxin. Some of these signals include the amount of daylight, temperature and overall climate where the plant lives. Adams said one thing we know is that plants can respond to different kinds of signals from the environment. I started to wonder why we see these kinds of changes in chemicals. The leaves detach from the tree and fall to the ground-with help from gravity and the wind, of course. When there is too much ethylene in the tree, the building blocks that make up the leaf will start to die. Scientists call this the abscission zone. But when fall comes around, the tree starts making less auxin and more ethylene at the place on the plant where the stem attaches to the leaf. In summer, the tree makes a lot of auxin. “There are these two chemicals, and they are sort of fighting it out throughout the year,” Adams said.

Meanwhile, a chemical called ethylene helps flowers open, fruit ripen and leaves fall. The chemical that helps a tree keep its leaves is called auxin. It turns out there are two main chemicals that play a part in whether the leaves stay on the tree or fall to the ground. He reminded me that all year long trees make their own chemicals that help control how they grow. To find out exactly what happens when leaves fall, I talked to my friend Henry Adams, a researcher at Washington State University.Īdams is very curious about the lives of trees and how they can survive harsh conditions. You’re right, each year during the fall, we often see a lot of trees dropping their leaves.