botany Botany, also called plant science, is the branch of natural science and biology studying plants, especially Plant anatomy, their anatomy, Plant taxonomy, taxonomy, and Plant ecology, ecology. A botanist or plant scientist is a scientist who s ...

, a stipule is an outgrowth typically borne on both sides (sometimes on just one side) of the base of a leafstalk (the petiole). They are primarily found among dicots and rare among monocots. Stipules are considered part of the anatomy of the

leaf A leaf (: leaves) is a principal appendage of the plant stem, stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leav ...

of a typical

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

, although in many species they may be inconspicuous —or sometimes entirely absent, and the leaf is then termed ''exstipulate''. At the other end of the scale are species like ''

Artocarpus elasticus ''Artocarpus elasticus'' of the Mulberry Family (Moraceae) and commonly called terap nasi or terap, is a rainforest tree of maritime and mainland Southeast Asia, growing up to (occasionally as much as 214 feet (65 meters)) in height with a dia ...

'' where the stipules can be up to eight inches (twenty cm) in length. (In some older botanical writing, the term "stipule" was used more generally to refer to any small leaves or leaf-parts, notably prophylls.) The word ''stipule'' was coined by

Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

''Concise English Dictionary'' Wordsworth Editions Ltd. 1994, from

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

''stipula'', straw, stalk.

Types of stipules

General characteristics

The position of stipules on a plant varies widely from species to species, though they 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 leaf. 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 are morphologically variable and might appear as

gland A gland is a Cell (biology), cell or an Organ (biology), organ in an animal's body that produces and secretes different substances that the organism needs, either into the bloodstream or into a body cavity or outer surface. A gland may also funct ...

s, scales, hairs, spines, or laminar (leaf-like) structures. If a single stipule goes all the way around the stem, it is known as an ochrea.

Types

According to duration

The three types of stipules according to duration are

caducous Dehiscence is the splitting of a mature plant structure along a built-in line of weakness to release its contents. This is common among fruits, anthers and sporangia. Sometimes this involves the complete detachment of a part. Structures that op ...

, 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.

According to shape, size and position

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 to the other stipule from the same node. A stipule is "adnate" if it's fused together on part of the petiole length, but the anterior is still free. A stipule is "interpetiolar" if it is located in between the petioles, as opposed to being attached to the petioles, and generally one stipule from each leaf is fused together, so it appears that there's just one stipule between each leaf. A stipule is "intrapetiolar" if it is located in the angle that is between a stem and a petiole. In this case, the two stipules generally form together and appear to be one stipule. A stipule is "ochreate" if a single stipule appears to be a solid tube that goes all the way around the stem. A stipule is "foliaceous" if it is leaf-like. These are generally used to photosynthesize. A stipule is considered a "bud scale" if it is hard or scaly and protects leaf buds as they form. These generally fall off as soon as the leaf unfolds. A stipule is considered "tendrillar" if they are long thin tendrils, and are generally used by climbing plants. A stipule is considered "spiny" if they are long and pointy. These are generally used to deter animals. A stipule is considered to be "abaxial", "counter" or "leaf opposed" if it is located on the opposite side to where the leaf meets the stem.

Purpose of stipules

Stipules have various functions. Some stipules are not well understood or may be vestigial. It is known that foliaceous stipules are used like leaves to make energy for the plants. Sometimes stipules protect the next leaf or bud as it grows in then falls off after the leaf unfolds, as with Tulip Poplars. Stipules can be used as climbing tendrils by climbing plants. Spiny stipules can be used to help protect the plant from animals.

References

General references

* Esau, K. 1953. Plant Anatomy. Second Edition. John Wiley & Sons, Inc., New York, London, Sidney. 767 pp.

External links

Stipules and stipels
__NOTOC__ {{Authority control Leaf morphology