What is a Seed?

Posted by Katie Elzer-Peters
March 6th, 2009
Filed in Seed Starting
Tags: flowers, seeds, vegetables

I’ve been beatin’ y’all over the head re: it’s time to plant your seeds.  Do you even know what a seed is?  You probably remember being in first grade when the teacher gave each student a bean seed, a cup and a paper towel.  You put the towel in the inside of the cup, and then put the bean seed between the cup and the towel, and wet the towel.  Then you watched the seed sprout.  Cool!  Do you remember the parts of the seed?  How seeds are made? How to store seeds?  How to plant and take care of seeds?  If not, here is a little primer for you.

Seeds are Baby Plants

That might seem like a bit of oversimplification, but, in essence, that is what they are.  To learn about seeds, first we start with the parts of a seed.

Seed Coat: This is the protective covering around the seed.

Endosperm: Food for the plant embryo to use until it sprouts and can produce its own food.

Cotyledons: “Seed Leaves”  These are the first little leaves that you see when the plant sprouts.  They are fully formed, inside the seed.

Hypocotyl: The stem of the plant embryo.

Radicle: The root portion of the embryo.  It pushes out and down to become a root, and breaks a hole in the seed coat so the cotyledons can push out and grow upward.

Seeds are made when pollen from one plant is transferred to another plant (or the same plant, if self-pollinating), “fertilization.”  The seeds form in the ovary of the flower, which turns into a fruit.  Some fruits are soft-like tomatoes.  Other fruits are hard, like maple tree seeds, “helicopters.”

How do Seeds Grow?

In general, for seeds to remain “viable,” which means “they will germinate,” they need to be kept in an environment where the humidity and temperature levels equal less than one hundred degrees f.  So, if the temperature is 60 degrees, the humidity should be no more than 40%.  The temperature and humidity affect seeds in two ways.

1. Seeds are alive.  They are just metabolizing incredibly slowly.  Plants metabolize faster at higher temperatures.  Hence, the need to keep temperatures low.
2. Humidity and/or water are factors in helping the seed germinate.  Seeds exposed to high humidity will metabolize faster, as well, but not fast enough to grow, and potentially not where you want them to grow. (You don’t want them to sprout in the packet!)

Below, is a diagram of a seed sprouting and growing.

We call the first leaves a plant produces after the cotyledons “True Leaves.” Often, you want to wait to transplant your seedlings until they have at least one pair of true leaves, if not two.

The seed has everything it needs inside of it in order to grow and produce its first true leaves.  Ater that point, it begins to photosynthesize to make its own food and the root system will soak up water.

This is a pretty simplified version of what a seed is, how it is stored, how it is produced and how it grows.  Hopefully, this little botany lesson will help you in your seed starting this spring.  Remember-moist (not drenched!) conditions and higher temperatures help your seeds grow faster!