The Collaborative International Dictionary
Petiolule
Petiolule \Pet"i*o*lule\, n. [Cf. F. p['e]tiolule.] (Bot.) A small petiole, or the petiole of a leaflet.
Wiktionary
petiolule
n. (context botany English) The petiole of a pinna or pinnule.
WordNet
petiolule
n. the stalk of a leaflet