Adjective
Being between petioles. Cf. Intrapetiolar.
Source: Webster's dictionaryDescription The Rubiaceae are morphologically easily recognizable as a coherent group by a combination of characters: opposite leaves that are simple and entire, interpetiolar stipules, tubular sympetalous actinomorphic corollas and an inferior ovary. Source: Internet
Characteristic for the Rubiaceae is the presence of stipules that are mostly fused to an interpetiolar structure on either side of the stem between the opposite leaves. Source: Internet