If you are new to growing and thinking of planting some seeds then this might be useful. There are a lot of new terms to come to terms with. Here are the new and the true leaves explained simply.
The first leaves are the Cotyledons, also known as Seed leaves. They are part of the seeds’ embryo and are there to provide nutrients to the seedling until its true leaves grow and begin photosynthesis to feed the seedling. Marvelous stuff. Here are some for you.
The first leaves, Cotyledons, are part of the plant embryo.
Seed leaves on a cucumber.
Seed leaves on a pumpkin.
The True leaves appear above the Cotyledons on the seedling. These look like the plant’s adult foliage only smaller.
True leaves on a lovely wee tomato.
True leaves appearing on spinach.
Nice glossy true leaves with good structure compared with the Cotyledons
Two tiny true leaves forming.
I hope that helps. For a super clear example, plant a bean and watch it grow. A lovely way to pass some time.