Leaf stomata

Types of stoma

In the mature leaf, four significantly different types of stoma are distinguished by their form and the arrangement of the surrounding cells, especially the subsidiary cells (Fig. 2)

• The anomocytic (irregular-celled) type; the stoma is surrounded by a varying number of cells, generally not different from those of the epidermis.

• The anisocytic (unequal-celled) type; the stoma is usually surrounded by three or four subsidiary cells, one of which is markedly smaller than the others.

• The diacytic (cross-celled) type; the stoma is accompanied by two subsidiary cells, the common wall of which is at right angles to the stoma.

• The paracytic (parallel-celled) type; the stoma has two subsidiary cells, of which the long axes are parallel to the axis of the stoma.

In describing an epidermis where certain stomata differ from the predominant type, the term applying to the majority of stomata is used.

anomocytic stomata                                                  anisocytic stomata

1 

dicytic stomata                                   paracytic stomata

Fig.2. Types of leaf stoma