One of the stages of plant growth that most people miss out on is the emergence of the cotyledons, or “seed leaves.” The cotyledons are part of the seed embryo–that is to say, they are already in the seed and merely expand and unfold as the seed germinates. If you want the complete explanation, check out wikipedia. In metaphorical terms: If the process of growing from seed is compared to a rocket blasting off, germination is like ignition. The cotyldons are like booster rockets that help the plant get into orbit. After the cotyldons come the true leaves, which are like solar panels that capture energy (think of the massive arrays on the International Space Station).
Science aside, part of what I find fascinating about the cotyledons is that they often bear no resemblance to the true leaves. Can you identify the plants below?