Cross section of a root

Cross section of a root
Cross section of a root: axis of the plant which grows in the opposite direction from the stem, maintain the plant in place and absorbs nutrients.
Piliferous stratum: set of cells on the outer layer that carry the root hairs.
Cortex: part of the root that protects the pith.
Xylem: woody parts of the root.
Phloem: vessels through which sap circulates.
Pith: central part of the root.
Phellogen: part of the root that produces cork.

Photo :

EN : Leaf margin
FR : Bords du limbe
ES : Bordes del limbo

Leaf 
          margin

The leaf margin is characteristic for a genus and aids in determining the species.