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How do conifers, holly and acorns (oaks) disperse their seeds?
Question Date: 2001-10-16
Answer 1:

One of the cool things about science is that sometimes you can figure out the answer to something you don't know by thinking about it in terms of things you do know. Conifers, holly, and oaks are very specific types of plants. It might take a lot of time looking through books to find something that says how each of these particular plants disperses its seeds. However, if you look at the question in a more general sense, and then consider what you do know about these plants, you can make a very good guess as to how these plants probably disperse their seeds.

First, how many ways can you think of that a plant could disperse its seeds? There are many believable possibilities. Maybe a plant could have its seeds blown far away by the wind. Maybe its seeds could fall in the water and be carried away by a river or stream, or float across a lake or ocean. Maybe the plant could somehow "throw" or "shoot" the seeds. Maybe the seeds could be moved places by an animal, either because the seeds got stuck to it or because the animal carried them on purpose. You might think of even more ways a seed could get moved somewhere.

Now that you've thought of some ways a seed might get moved, the next thing to do is to think about what you know about the seeds of conifers, holly, and acorns, and from that determine which of the above seed dispersal mechanisms seems the most likely.

Conifers produce their seeds inside cones (ie, pine cones). A pine cone probably couldn't be blown very far by the wind while it falls, unless the seeds were to come out of the cone and get blown somewhere before the cone fell. However, seeds that are dispersed by wind normally have shapes that help them get carried in air, such as tufts of "hair" or wings. A pine cone could certainly be transported by water, but the problem with that idea is that conifers are land plants, and can't really grow in the water. So the seed might drown in the water, and the conifer couldn't grow unless the pine cone were to somehow get pushed or pulled out of the water and onto the land. I've seen lots of pine trees growing far away from water, so this doesn't seem like a very likely mechanism. I've also never seen pine cones shooting seeds out, so this doesn't seem like a likely dispersal mechanism either. I have, however, seen birds pecking at pine cones, and people kicking them. It makes a lot of sense, then, that birds or people or maybe even other animals could be moving the pine cones, or the seeds that are in them.

Going through a similar thought process with acorns and holly, it seems evident that they wouldn't be transported by wind, water, or launching. However, holly produce nice red berries (which we've all seen in Christmas decorations) that look like they might be awfully tempting to animals, especially birds.

Why would a plant produce something tasty for animals to eat? It doesn't seem like it would benefit a plant to get eaten, unless it produces the fruit to attract an animal so that the animal will transmit its seeds. This certainly makes sense, since even we humans throw the seed (or pit) away after we eat a piece of fruit-- effectively dispersing the seed (have you ever bitten into a grape with seeds in it? The first thing you do is spit the seeds back out on the ground!). Acorns also don't look well-suited to any of the forms of transport except for by animals. Chipmunks (like the Disney characters Chip and Dale) and squirrels like to hide acorns in order to store them for later, and sometimes they might forget where they hid them, allowing them to grow into new plants. Birds and other animals might also try to eat acorns, carrying them away from the tree in the process. Birds, such as the blue jay, can carry acorns especially long distances since they can fly.

So it seems likely that the most important mechanism of seed dispersal for all three of these plants is transport by animals. (This also includes the deliberate planting of seeds by people!

If you plant a tree in your yard or vegetables in your garden, you have transported some seeds!) This doesn't mean that other mechanisms aren't also at work. Sometimes a strong wind might blow a seed, or a seed might fall into the water and later get washed up on land. But the most common method of dispersal is through animals.

Answer 2:

Seeds of conifers, holly and oaks (acorns) may be dispersed directly from the plants by dropping when fruits mature. Some of these seeds and fruits may roll, or be blown along the ground. Some conifer seeds have seed wings, which increase the chances that they will be moved by wind.

Fruits and/or seeds of these plants may also be dispersed by animals. Fruits and berries may be eaten by a variety of animals. Many fruits have indigestible seeds, which pass through the animals digestive tracts.

Squirrels, Pigeons, Jays and Woodpeckers may even plant the seeds inadvertently. These animals store some of their fall harvests for food in the winter. The seeds may germinate from buried caches

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