What is the stem of a leaf called?

The stem of a leaf is referred to as the petiole. The petiole connects the leaf blade to the stem of the plant, playing a crucial role in supporting the leaf and facilitating the transport of nutrients and water to and from the leaf. Understanding this terminology is essential in horticulture and plant science, as it helps in identifying plant structures and their functions.

The other terms in the options also relate to parts of plants but do not specifically denote the part of the leaf that connects it to the stem. For instance, the stem generally refers to the main structural support of a plant, pestilence relates to disease affecting plants and is not a botanical term, while a node is a part of the stem where leaves attach, rather than referring to the leaf's connection itself. Therefore, petiole is the precise term needed in this context.