The palisade mesophyll is a layer of elongated cells containing chloroplasts found just under the upper epidermis. Just below the palisade mesophyll is an area of loosely packed parenchyma called the spongy mesophyll. The spongy mesophyll contains air spaces in which gases circulate. The petiole of the leaf connects the blade with the stem. The vascular tissues pass through with the xylem positioned in the top section of the vein ,while the phloem occupies the lower section.
Apical meristem is responsible for primary root and stem growth in vascular plants.
The apical meristem, is an area of rapidly dividing cells. It will replace the cells of the root cap as they wear away and push cells above them that will develop into the main tissues of the plant. The zone of elongation, is an area where the cells elongate 10 times their original length. This elongation helps push the root into the soil. The zone of maturation, is the area farthest from the root tip.