If stems and leaves look similar, how do you tell them apart; i.e. what is a diagnostic feature of stems?

Stems and leaves can often look similar, especially in certain types of plants. However, there are a few key characteristics that can help you distinguish between the two:

1. Position: Stems are usually central and continuous throughout the plant. They serve as the main support structure and transport system, connecting roots and leaves. Leaves, on the other hand, are typically attached to the stem.

2. Growth: Stems grow in a circular pattern around the plant, while leaves usually grow out of the stem in a branching pattern.

3. Structure: Stems are generally thicker and stronger than leaves. They need to be able to support the weight of the plant and withstand environmental conditions. Leaves are usually thinner and more flexible.

4. Function: Stems serve as the main transport system for water, nutrients, and sugars between the roots and the leaves. They also provide support for the plant. Leaves are the main site of photosynthesis, where sunlight is converted into energy for the plant.

5. Presence of Buds: Buds, which are the beginnings of new growth, are typically found on stems, not leaves.

6. Texture: Stems are usually rougher than leaves, which are generally smooth.

Remember, these are general characteristics and there may be exceptions depending on the specific type of plant.