Hidden beauties #11

Card 11 - A leaf slice

As can be seen from the following images, leaf structure can be quite varied, but the overall "plan" is quite similar. The upper epidermis protects the leaf and then underneath that is usually the palisade layer; this is the layer where most of the photosynthesis takes place, its cells are usually tall and cylindrical and well supplied with chloroplasts.. Beneath this layer are the more loosely packed and irregularly shaped cells of the spongy mesophyll layer; beneath that is the lower epidermis. Most of the stomata are usually found in this layer. Carbon dioxide enters the leaf through the stomata and diffuses through to the palisade cells to be combined with water (brought in from the root via the xylem tissue) to form carbohydrates using light energy from the sun.

Pampas grass - transverse section through leaf

Pinguilica (Butterwort) TS through leaf showing mucilage secreting hair which helps trap insects

Marram grass TS through leaf. Marram grass needs to conserve water so the leaf is curled, stomata are situated in pits,.

TS through the leaf of a xerophyte (a plant that lives in dry conditions) - its epidermis is thick to reduce water loss  by transpiration, its stomata are in pits which are surrounded by hairs to increase humidity around them and so reduce water loss by transpiration.

More information can be found in this article I wrote for Microscopy UK