Abaxial

The underside of a leaf; which is the surface facing the ground.

  Adaxial

The upper side of a leaf; which is the surface which typically contains the most stomata. It is the surface which is enclosed within a rolled or folded leaf.

  Adventitious Root

Roots that develop from non-root tissues, such as nodes on rhizomes or stolons. They are not developments from primary and lateral roots.

  Anatomy

The internal structure and arrangement of plant features. This looks at plant cells and their arrangement into different plant tissues. Examples include: xylem; phloem; palisade cells; and sclerenchyma.

  Androecium

The collective name for Stamens.

  Anther

A small feature at the end of a filament which contains and produces pollen.

  Ascending Plant

A plant that grows in an upward, but not upright, direction, which is typical of many shrubs.

  Auricle

A small, often grasping, claw like feature in some grasses at the base of a leaf blade. Auricles are present in some grasses, for example in Perennial ryegrass and Couch grass.

  Awn

A very fine bristle which projects from some grass seeds, such as red fescue (Festuca rubra ssp), or very prominently such as on sweet vernal grass (Anthoxanthum oderatum).

  Axillary Bud

A bud (also called an embryonic shoot) that is located at a leaf node; this is where the leaf joins the stem (known as the leaf axil) and from where a new leaf can emerge.