Stipule of Leaf – Functions and Types

Stipules of the leaf are tiny, leaf-like structures normally present in certain plants near the base of the petiole, the leaf stalk. They are found on each side of the petiole’s base, where it connects to the stem, and are frequently paired. Depending on the type of plant stipulates might differ in size, shape, and appearance.

Some stipulate leaf examples are seen in roses, sweet peas, acacia, and china roses. In this article, we will learn about stipules, their types, functions, and examples of stipules.

Stipule Meaning

Stipules are tiny, leaf-like structures that certain plants have at the base of their petioles, or leaf stalks. These structures are frequently paired on either side of the petiole where it affixes to the stem. The size, form, and appearance of stipules vary significantly; they might be little, hardly noticeable scales or huge, clearly defined leaf-like structures. Stipules are a characteristic shared by many dicotyledonous plants; however, they are not found in every species.

Types of Stipules

There are many different kinds of stipules, and different plant species may have rather different stipule features. These consist of:

1. Free Lateral Stipule: Members of the Malvace family, these stipules are located near the base of the petiole. For example China Rose.
2. Adnate Stipules: These are the second kind of stipules, where two stipules are joined together to give the impression that they are wings. For instance, Rosaceae
3. Foliaceous stipules: Foliaceous stipules have been completely developed and resemble leaves, sometimes even more so than the actual leaves on the plant. Compared to other kinds of stipules, they are more common and can aid in photosynthesis. Example – Sweet Pea.
4. Spiny and thorny stipules: Stipules can be altered to resemble thorns or spines in certain plants. These altered stipules protect the plant by repelling animals and acting as a defensive mechanism. Example – Thorny Acacia.
5. Glandular Stipules: The glands in glandular stipules can release different compounds, such as oils or nectar. These stipules could help draw pollinators or discourage herbivores.
6. Tendrillar stipules: Stipules on certain plants have been transformed into tendrils, which are thin, spiralling appendages that help plants climb or provide them more support. Example – Greenbrier.
7. Intrapetiolar Stipules: Stipules that are positioned on the leaf’s axle and present on both sides of the opposing leaves. The inner edge unites the leaves in this instance. It is a member of the Rubiaceae family.
8. Interpetiolar Stipules: Stipules of the interpetiolar category are tiny lanceolate entities connected by the leaf margins. For example, Anangan
9. Convoluted stipules: It is also known as bud stipules, are stipules that have changed into structures that resemble membrane scales that envelop and shield buds. For instance, Indian Banyan.
10. Ochreate stipules: These sheath-like, simply tubular stipules envelop a greater portion of the internode. This kind has many stipules that come together to create a protective sheath. It is a trait unique to the Polygonaceae family. Polygonum is an example. Example – Knotweed.

Based on Duration

There are three distinct kinds of leaf stipules according on duration: caducous, persistent, and deciduous.

1. Deciduous stipules: Deciduous stipules are temporary stipules, which fall off as the plant ages.
2. Persistent stipules: Stipules can be persistent, remaining affixed to the plant for a considerable amount of time.
3. Caducous stipules: Caducous stipules fall off before the leaf unfolds.

Stipule of a Leaf Functions

In plants, stipulates have a variety of purposes, and these purposes might change based on the species. The following are some typical uses for stipulates:

1. Protection: Stipules can serve as structural barriers, covering and protecting tender, growing leaves or flower buds. This defense aids in preventing harm from external factors, herbivores, and unfavorable weather.
2. Conservation of water: Certain stipules have been modified to help preserve water. They could envelop the base of the leaf, cutting down on water loss from transpiration and adding another line of defense against drying out.
3. Defense: Stipules that have been altered, such thorny or spiny stipules, serve as a protection against herbivores. The plant provides a natural defense mechanism by discouraging animals from eating on its sharp features.
4. Support: Tendrils are thin, spiraling structures that aid in plant climbing or provide as extra support. Some plants are able to discover adequate structures for support or access sunlight thanks to this adaption.
5. Pollination: Glandular stipules have the ability to release oils or honey, which draws pollinators like ants and bees. By fostering a mutualistic relationship between the pollinator and the plant, this promotes pollination-based reproduction.
6. Photosynthesis: Stipules can be actively photosynthetic under certain situations, which increases the plant’s total photosynthetic potential. Particularly foliaceous stipules have the ability to produce chlorophyll and perform photosynthesis.
7. Taxanomic identification: In taxonomic categorization and identification of plants, stipulates are important. Differentiating between various plant families and species might depend heavily on the presence, absence, and features of stipules.
8. Symbiotic relationship: Stipules and other organisms can have symbiotic interactions. For instance, certain stipules include unique features that support mutualistic bacteria and aid in the nitrogen fixation in specific leguminous plants.

Stipulate Leaf Examples

Stipules can change amongst plant species and can take on a variety of shapes. Here are some instances of stipules in various plants:

1. Phaseolus plants or beans: They have tiny, membrane-covered stipules near the base of the leaf petiole on many of their plants.
2. Rose (Genus: Rosa): Roses are distinguished by their frequently leafy stipules, which can resemble tiny, tooth-like features at the base of the leaf stalk.
3. Okra (Abelmoschus esculentus): Stipules on okra plants are usually big, deeply lobed, and palmate, kind of like extra little leaves.
4. Blackberries (Genus: Rubus): Large, sharp stipules that protrude from blackberry bushes shield the buds that are still forming.
5. Peaches (Prunus persica): Small, hardly noticeable stipules may be present at the base of the petiole of leaves on peach trees.

Conclusion: Stipule of Leaf

To conclude, stipules are small, leaf-like structures that are present at the base of some plants’ petioles or leaf stalks display an amazing range of forms and purposes. These structures are essential to plant biology because they support plant adaptability, defense, and ecological interactions. The diversity of stipule forms, which include leaf like, scale like, spiky, glandular, and more demonstrates how these structures may be found in a wide range of plant species.

FAQs – Stipule of Leaf

What are the Different types of Stipules in Leaf?

Stipules, diverse in nature, manifest in several distinct forms, including Free-lateral, Adnate, Intrapetiolar, Interpetiolar, Ochreate, Foliaceous, Tendrillar, Spinous, and Bud scales.

What is the Function of the Sipule of a Leaf?

Stipules play a protective role during the initial growth of a leaf or bud, only to gracefully detach once the leaf unfurls, exemplified by instances such as tulip poplars.

What is Difference between Stipule and Bract?

Stipules, modified paired structures, are situated at the leaf base, while bracts, similarly modified, are found at the base of the inflorescence.

What is the Difference Between Petiole and Stipule?

Petiole is the stalk that connects a leaf to the stem, while stipule is a small, leaf-like structure found at the base of the petiole or leaf stem, often varying in shape and size between plant species.

What is Stipule and Ligule?

Stipule are small leaf-like structures at the base of a leaf’s petiole while ligule are thin, membranous or hairy structure in grasses, located at the leaf blade-sheath junction.

What is the Location of Stipule?

In angiosperms, leaves typically feature stipules – paired structures positioned on either side of the leaf base, exhibiting diverse forms such as scales, spines, glands, or leaf-like appendages.

Are Stipules present in all Plants?

Not all cells possess stipules. They may be inconspicuous or entirely absent in certain instances.