Final answer:
Plants have different types of stems. Some have stems that grow horizontally, while others have very short stems or rosette formations. Stem diversity allows plants to occupy different ecological niches.
Step-by-step explanation:
Although most familiar plants have a main stem and branches that grow upwards, this is not always the case. Some plants have stems that grow horizontally, producing a 'prostrate' growth form. Other plants, like dandelions, have very short stems that are not easily visible because their leaves are closely clustered in a rosette formation. Stem diversity is also seen in specialized stems that allow plants to exploit different ecological niches.