You learn that it's common along roadsides and railroad tracks and that the Indians used to boil its potato-like tubers as an important food. You leave the park thinking that now you know the Jerusalem Artichoke. So, one day you want to show a Girl Scout troop what wonderful tubers the Jerusalem Artichoke has. You dig up a plant looking the right way, but there are no tubers. In other words, the plant world is organized in such a way that sometimes plants are so unique in their appearance that you'll never misidentify them, even when they have no blossoms, but, more frequently, plants have look- alike relatives that may or may not possess the qualities in which you're interested.
Flowers are sexual organs.
As we'll see later, flowers are not the only way nature has figured out for plants to reproduce themselves. In contrast, the first plants with flowers appeared only about 135 million years ago. However, flowers proved to be such wonderful innovations that, once they appeared, flowering plants spread over most of the earth, often driving nonflowering plants from their habitats. If you look out of your window right now, unless you have coniferous trees such as pines, spruce, or fir around you, there's a good chance that all the plants you see will be flowering plants. But, back to the fact that flowers are sexual organs.