Leaf margins and surface features

Leaf margins

The leaf margin (or leaf edge) may be smooth or variously toothed or scalloped.

  • A smooth magin (not toothed in any way) is called an entire margin.
  • A toothed margin is sometimes called "dentate" (meaning "toothed")
  • If the teeth slant toward the tip of the leaf, however, the margin is called serrate.
  • Sometime large serrations have smaller serrations on them. These margins are called doubly serrate.
  • A crenate margin has rounded teeth with acute sinuses between the teeth. (It is scalloped.)

Leaf margins
Leaf margins (entire, crenate, dentate, serrate, and doubly serrate margins). [Drawings by Bob Muns]

Leaf hairs may cover the surface of leaves (below), but if hairs are on the margin, rather than the surface, the leaf is called ciliate.

Leaf surface features

 Leaf surfaces may have various types of hairs, bumps, or color and sheen.

Glabrous surfaces have no hairs.

Glaucus surfaces are glabrous, but the cuticle structure gives the surface a white, milky look.

Glaucus vs green leaf
Glaucus vs. green. Both leaves above are glabrous. However, the one on the left is glaucus, whereas the one on the right is green.

 Hairy surfaces may be described in different ways, depending on the structure of the hairs.

Hairs may be simple (unbranched), branched or forked, or stellate (with many branches radiating from a central point).

Hairy surfaces may be described as...

  • puberulent, if the the hairs are short, fine, and soft
  • canescent, if the hairs are dense, fine, and generally grayish white
  • villous, if the hairs are long, soft, and wavy
  • tomentose, if the hairs are wooly and matted
  • strigose, if the hairs are straight, stiff, appressed, and pointing the same direction
  • scabrous, if the surface is rough to the touch. This is usually caused by very short, stiff hairs or sharp bumps.

Hairs and fruit shapes from the Jepson manual
This figure, from the Jepson Manual, shows margins with hairs, different types of hairy surfaces, and different types of hairs. It also illustrates terms used to describe fruits, which we have not discussed.

Some surfaces may have glandular hairs or sunken glands.

Leaf surface of Helianthus annuus
Leaf surface of Helianthus annuus. Long, stiff, non-glandular hairs and short glandular hairs are both present. Drops of oil or resin secreted by the glandular hairs are the most visible signs of glandular hairs. [Photo by Kassandra Leon, BIOL 354, 2019]

Check your understanding:

Juniper leaves
Juniper leaves

Oak leaf
Oak leaf

Prunus virginiana
Prunus virginiana

Rhus ovata
Rhus ovata

Bushmallow hairs
Bushmallow hairs

Eriogonum wrightii
Eriogonum wrightii

Leaf X
Leaf X