What germination is
The embryo within a seed becoming active and growing, so that a seedling comes into being, is called seed germination.
A seed is a plant that has been paused. Inside it lies the embryo from the fertilised ovule, a store of food packed around it, and a coat holding both. All of that may sit unchanged for months. Germination is the moment it restarts.
What comes out, and in what order
Two structures grow out of the embryo:
- the radicle, which becomes the root;
- the plumule, which becomes the shoot.
The radicle almost always emerges first, and it grows downwards. A seedling secures its water supply before it spends anything on leaves.
The end of the sexual cycle, and the start of it
Germination closes the loop this section opened. A flower made gametes, fertilisation made a zygote, the zygote became an embryo inside a seed, the seed travelled — and here that embryo becomes a plant that will one day flower itself.