stipule A leafy or linear appendage, found, usually in pairs, at or near the base of the petiole of a leaf. Stipules are often variously patent (i.e. spreading), but may be adpressed to petiole or twig. Occasionally they are amplexicaul (i.e. surrounding and clasping the twig). These uncommon positions are valuable aids to plant identification.

stipule An outgrowth from the petiole or leaf base of certain plants. Those of the garden pea are leaflike photosynthetic organs. The stipules of the lime tree are scalelike and protect the winter buds, whereas those of the false acacia (Robinia) are modified as spines.