why do pine trees have pine cones
WBZ Normally this time of year, you might have snow covering your yard, but if you have a pine tree or two, chances are you have a slew of pine cones blanketing the ground. That spurred Maggie in Chelmsford to I m curious about the pine trees this year having excessive amounts of pine cones. I can t ever recall seeing so many. Scientists confirm the trees are producing an unusually large amount of pine cones this year. Maureen Foley of Jamaica Plain can hardly take a step in her front yard without crushing one. At one time I would be going around scrounging for pine cones because I was into doing some crafty stuff and couldn t find them, she said. But I have more than enough now that s for sure. This year s bumper crop is hard to avoid. They re in yards, parks, along roadways. Runners in the Arnold Arboretum in Boston had to dodge them, or plow through them on the trails. It s definitely an abnormal amount of pine cones, said Peter DelTredici, Senior Research Scientist at the Arnold Arboretum. Deltredici says the pine cones falling from the trees now, actually started forming three years ago, so our winter weather isn t to blame for the bumper crop. He says scientists believe it probably has to do with the insect population. Pine trees don t produce the same amount of cones each year, he says, to throw off the insects that eat the cones.
Trees do this as a way of avoiding these predators, because if they produce the cones on erratic, unpredictable cycles the insects can t adjust to them. And while some people might complain about the mess, scientists say a tree s good far outweighs any maintenance. If you want a tree that doesn t produce something those are really only plastic trees, said DelTredici. Trees are so great the fact that we have to clean them up once a year, that doesn t seem too much to me. Maureen Foley agrees, as she looks at the massive pine that has dumped hundreds of cones on her front lawn. This guy is a treasure. Scientists say you can expect to see these bumper crops about every three to seven years. MMX, CBS Broadcasting Inc. All Rights Reserved.
Trees, like all living organisms, employ a variety of strategies for reproducing. Pine trees have evolved special structures, the pine cone, as a central means of reproduction. The pine cone is key to successful fertilization of seeds and assists plays an important role in dispersing seeds over a wide area. A single pine tree ordinarily contains both male and female pine cones. Pine trees reproduce by producing seeds. Unlike deciduous trees, which produce seeds that are surrounded by fruit, pine seeds are located on scales of structures called cones (pine cones).
Pine trees possess both male and female reproductive structures, or cones. Both male and female cones are on the same tree. Typically, the male cones that produce pollen are located on the lower branches of the tree. This is to prevent the pollen from falling on the female cones of the same tree and, thus, promotes fertilization with other pine trees, which enhances genetic variation among trees. The male cones, also known as catkins, are present only during the spring of the year when they are producing pollen. They do not look like the pine cones many are familiar with, but are long thin structures that are soft and located in clusters on the branches. Pollen is produced by the male cone. A grain of pine pollen contains the genetic information from the pine tree on which it hangs. Each grain of pollen is equipped with two small wing-like structures that help the pollen become aloft in the air and promote a wide distribution. The grain of pollen then finds its way to a receptive female cone, which appears to be solid and hard. Once the pollen lands on the cone, it grows a long thin tube into the center of the cone where the egg is located.
There, the genetic information in the pollen grain is combined with the genetic information in the egg, and a fertilized embryo results. As time passes (usually about two years), the embryo grows into a seed and the cone becomes brown and develops scales. It is at this time the pine cone resembles the familiar cones seen littering the forest floor. If one of the pine cone's scales is pulled off, a mature seed can be seen at the base. If planted, this seed will grow into a pine tree. Because plants are immobile, it is important that they have ways to disperse their pollen and seeds away from the parent plant to minimize inbreeding. The winged pollen that pine trees have helps this dispersal. Various animals such as squirrels and jays commonly eat pine seeds and disperse them. Pine nuts (seeds) also are becoming a large part of human cuisine (although humans do not disperse these seeds, obviously). Because animals do not eat all species of pine cones, some species have developed unique ways to prevent inbreeding. Some pine cones remain tightly closed until they reach an extremely high temperature, as would be present in a forest fire. Only when these cones are heated do they release their seeds, which corresponds to the likely death of the parent plant in the fire.
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