Final answer:
The slender stalk that connects the flattened leaf blade to the stem in most dicots is the petiole.
Step-by-step explanation:
The slender stalk that connects the flattened leaf blade to the stem in most dicots is the petiole. The petiole is the stalk that extends from the stem to the base of the leaf. It helps support the leaf and allows nutrients and water to flow between the leaf and the stem.