petiole

English edit

WOTD – 11 January 2012

Petioles between leaf blades and stem.

Borrowed from French pétiole, and its source, Late Latin petiolus (“little foot”), diminutive form of Latin pēs (“foot”).

petiole (plural petioles)

(botany) The stalk of a leaf, attaching the blade to the stem.
Synonym: pedicel (stalk of a flower)
- 1978, Harry T. Valentine, Estimating Defoliation of Hardwoods Using Blade-petiole Relations, Forest Service Research Paper NE 405, US Department of Agriculture, page 1:
  Most insects consume tissue from the leaf blade were measured just past the twist on the side away only, leaving the leaf petioles unscathed.
- 1992, Karl J. Niklas, Plant Biomechanics‎^[1], University of Chicago Press, page 167:
  By contrast, the petioles of large pinnate leaves, as well as stems, typically resist torsion by placing stiff materials with high elastic moduli (like sclerenchyma) toward the perimeters of their cross sections.
- 2000, Mike Hansell, Bird Nests and Construction Behaviour‎^[2], Cambridge University Press, page 116:
  An example of this is leaf petioles. Some species of trees have pinnate leaves which, when the leaves fall, shed pinnae from the petiole, which is then left as a tapering, somewhat flexible rod.
(entomology, insect anatomy) A narrow or constricted segment of the body of an insect; especially, the metasomal segment of certain Hymenoptera, such as wasps.
Synonym: pedicel (used more generally, of arthropods)
(entomology) The stalk at the base of the nest of the paper wasp.

The presence of a petiole (narrow body segment) is the defining characteristic distinguishing the suborder Apocrita (ants, bees and wasps) from the rest of order Hymenoptera (i.e., from the paraphyletic suborder Symphyta).

stalk of a leaf