A stipular spine is located at the leaf base of Erythrina flabelliformis (Family Fabaceae). This species mostly grows as a small tree in thorn scrub and thorn forest of the Sonoran Desert region. The swollen base of the leaf is a pulvinus, which can be used by the plant to position the leaf. The stipule looks like an outgrowth of the stem, but actually is a part of the leaf.