When a seed germinates, how does it knows which direction is up?
In: 90
There’s tons of different methods plants use , and it’s really hard to say which one is the most used
But here’s a few them an small eli5 of each
1. Water gradients/nutrient gradients. So I want you to think of a coffee filter with coffee grounds on it , when you pass that hot water through it you get coffee come out the bottom since the water dissolved and carried some of the stuff with it down , well as water gets more saturated with stuff less can dissolve into it , this means that a small gradient will form of more nutrients as you go deeper , seeds can use that gradient to determine which direct water is flowing in to send their roots which is often down but also how you get roots that grow along surfaces as well
2. Gravity. As much as seeds are pretty solid , just like you and me they have some little bit of movement as they grow , some of these bits that grow are denser then the others so essentially settle near the bottom from gravity which can usually signal where the root should shoot out
3. Heat. The vast majority of seeds are designed to be on the surface or barely covered after being dispersed , usually it’s during a time when the air is generally much warmer then the ground so even when submerged the top layer are warmer then the lower ones so by using temperature they can tell what side is likely the surface , some seeds even need heat to germinate since it’s part of how they tell it’s time to grow
4. Light . This one is the most basic and easy to understand , plants use light to make food and will grow towards it , they often will shoot roots in the opposite direction.
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