|
|
Leaves typically have broad, flat regions that are specialized to collect light for photosynthesis. We eat leaves of various plants, including artichokes, celery, lettuce, onions, and spinach among others. Each of these plants has very different looking leaves. Let's begin by considering the parts of a "normal" leaf.
A "normal" leaf leaf has three morphological regions: 1. base, 2. petiole, and 3. lamina. The leaf lamina is typically a broad, flat region with extensive surface area to collect light for use in photosynthesis. The petiole is a stalk-like region of the leaf that functions to hold the lamina away from the stem of the plant, perhaps to provide greater access to light. The leaf base is a broad area at the lower end of the petiole where the leaf joins the stem. We can see these three morphological regions of typical leaves if we look at spinach.
|
|
|
When we purchase spinach in the produce section of a grocery, we usually obtain an entire shoot system. This shoot system has a short stem with the set of leaves at closely positioned nodes. If we look at each individual spoon-shaped leaf, we can readily find the broad lamina at one end, the linear petiole, and, at the end of the petiole where the leaf attached to the stem, a slight broadening that constitutes the leaf base.
When we eat spinach, it is usually the flavorful laminas that we seek. This contrasts with celery, from which we typically eat the petiole. As with spinach, we often purchase a large piece of the celery shoot system from the grocery. This shoot has a stem with short internodes and numerous overlapping leaves. If we remove a single celery leaf, we can see the broad, stiff base that was attached to the stem. Above it is the edible petiole. At the end of the petiole, we find the upper portion of the leaf is divided into a numerous separate pieces, each of which represents a portion of the lamina. Leaves, such as those of celery, in which the lamina consists of separate parts are called compound.
|
|
Artichokes also have leaves that we eat. The artichokes we purchase for cooking are the ends of stems near the region where flowers are produced. In this region of the artichoke shoot, the internodes are short and the leaves overlap one-another. These oval leaves of artichokes do not have distinct lamina, petiole, and base regions such as we observed in spinach and celery. Instead, each leaf of an artichoke consists simply of an enlarged leaf base.
|
|
 |
|
|
|
 |
 |
 |
 |