bladstjälk

Bladstjälk, also known as a petiole, is the stalk that attaches a leaf blade to the stem of a plant. It is a crucial part of the leaf's anatomy, playing a role in leaf orientation and support. The petiole contains vascular tissues, xylem and phloem, which transport water and nutrients to the leaf and carry sugars produced during photosynthesis away from it.

The length and thickness of petioles can vary greatly between different plant species, and even within different leaves on the same plant. Some petioles are very short, making the leaf appear sessile (attached directly to the stem), while others can be long and slender, allowing the leaf blade to extend further from the stem. This extension can be beneficial for light capture, as it can help reduce shading of lower leaves by upper ones.

The shape of the petiole can also differ. It can be round, flattened, or grooved. In some plants, the petiole may have leaf-like appendages called stipules at its base, which can offer protection to the young leaf as it develops. The arrangement of petioles on the stem, along with the arrangement of the leaves themselves (e.g., alternate, opposite, whorled), contributes to the overall architecture of the plant. Understanding the structure and function of the bladstjälk is important in plant morphology and taxonomy.