Zea mays Leaf (monocot)




Zea mays (corn, a monocot) leaf cross section, 100X.
A = spongy mesophyll; B = upper epidermis; C = upper cuticle; D = xylem; E = vein; F = phloem; G = lower cuticle; H = stoma, I = guard cell, J = lower epidermis

Function:
The spongy mesophyll has air spaces for gas exchange and produces carbohydrates by photosynthesis. The upper and lower cuticle protect the leaf from water, sealing water inside and preventing excess rainwater from entering. The upper and lower epidermis produce the cuticle and protect the leaf from herbivores and parasites. The xylem transports water into the leaf while the phloem begins the sugar transport down to the roots. The guard cells open and close the stoma, which is the small air space between them.

Tissue Breakdown:
Epidermal tissue: epidermis.
Ground tissue: spongy mesophyll.
Vascular tissue: xylem and phloem.
Meristem tissue: none (leaves do not grow new leaves).

At 40X, micrograph width = 2 mm; at 100X, micrograph width = 0.8 mm; at 400X, micrograph width = 0.2 mm; at 1000X, micrograph width = 0.08 mm.