How do leaves form? how are they attached to the plant?

Xylem: cells that bring water and minerals from the roots into the leaf. Phloem: cells that usually move sap, with dissolved sucrose(glucose to sucrose) produced by photosynthesis in the leaf, out of the leaf. A sheath of ground tissue made of lignin surrounding the vascular tissue. thats how leaves are made

Some leaves have a petiole, which attaches the leaf to the stem; leaves that do not have petioles are directly attached to the plant stem and are called sessile leaves. ... In an opposite leaf arrangement, two leaves connect at a node. In a whorled arrangement, three or more leaves connect at a node. thats how they  r attach 

Air occupies