Stomata are small openings in the epidermis or surface of leaf, and leaves bearing them are said to be stomatic or stomatiferous. The petiole varies in length and shape and sometimes helps in the identification of species. Stipules vary a great deal in size, from mere threadlike appendages to those the shape and nearly the size of a small leaf. Stipules may or may not be persistent. When they fall, they leave a stipular scar on the twigs that is closely connected with the leaf scar.
Stipular scars vary greatly in size and shape from a small dot to a line that encircles the twig.
Stipules or their scars may be present or absent. When leaves fall, they leave a scar varying greatly in size and shape. These are usually consistent within the genus. These bundle scars vary in number and pattern and are often used as characteristics for winter identification. Measurements and Their Equivalents Measurements in standard botanical works are usually given in the metric system.