Exstipulate

In botany, stipule (Latin stipula: straw, stalk) is a term coined by Linnaeus which refers to outgrowths borne on either side (sometimes just one side) of the base of a leafstalk (the petiole). A pair of stipules is considered part of the anatomy of the leaf of a typical flowering plant, although in many species the stipules are inconspicuous or entirely absent (and the leaf is then termed exstipulate). In some older botanical writing, the term "stipule" was used more generally to refer to any small leaves or leaf-parts, notably prophylls.

The position of stipules on a plant vary widely from species to species, though are often located near the base of a leaf. Stipules are most common on dicotyledons, where they appear in pairs alongside each leaf. Some monocotyledon plants display stipule-like structures, but only display one per lear. If a single stipule goes all the way around the stem, it is known as an ochrea.

Stipules are morphologically variable and might appear as glands, scales, hairs, spines, or laminar (leaf-like) structures. A relationship exists between the anatomy of the stem node and the presence or absence of stipules: most plants with trilacunar nodes have stipules; species with unilacunar nodes lack stipules.

Stipules generally appear in pairs on opposite sides of the stem at the base of each leaf, though there's lots of variation in structure.

The three types of stipules according to duration are Caducous, Deciduous and Persistent. Caducous stipules fall off before the leaf unfolds, while Deciduous stipules fall off immediately after the leaf unfolds. Persistent stipules remain attached to the plant.

A stipules can be considered Free lateral, Adnate, Interpetiolar, Intrapetiolar, Ochreate, Foliaceous, Bud scales, Tendrillar or Spiny.

A stipule can be fused to the stem, or the other stipule from the same node.

Stipules are "free lateral" when a pair of small, green stipules are present, with one on each side of the base of the leaf.

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Wikipedia