The next great finding in the study of seed germination is what happens in lettuce seeds (Lactuca sativa). Lettuce seeds look somewhat different from barley seeds, because they are dicots. They also have separate seed coat and fruit walls. But the things you buy as lettuce "seeds" are really lettuce fruits (called cypselas). As different as they are, the seed germination process in lettuce needs just one step more than barley to get its seeds germinating.
Lettuce cypselas have very thin fruit walls and seed coats, so light can penetrate these coverings. As is typical of small seeds, light is needed to stimulate seed germination. One might wonder how this would fit into what we just found out with barley.
To keep things simple, I am not drawing a lettuce seed here, but am showing you what happens in lettuce seeds by attaching the additional step to the diagram of a barley seed we have been studying (remember lettuce is a dicot and lacks an aleurone, etc.):