Stem Definition, Characteristics of Stem, Stem Transformation, Stem Functions Work of Plant Stem in English

The stem is the part of the plant that grows against the ground and water and towards the light. The stem develops from the plumule and bears branches, leaves, flowers and fruits.

The stem is the ascending part of the plant, which moves against the ground towards the light. (Negatively geotropic but positively phototropic). The shape of the stem is cylindrical, flattened or angular. Buds are found at the tip of the stem, from which the stem grows.

Characteristics of Stem:

• The stem provides strength to the plant, which is due to the xylem and soloronchyma present in the stem.
• It gives rise to branches, leaves and flowers.
• It transports water and mineral salts absorbed by the roots to other parts and food synthesized in the leaves to other parts including the root.
• Stems have definite nodes and inter-nodes. Branches and leaves usually emerge from the hills.
• The stem also stores food like the roots. For example, potato, turmeric, ginger, sugarcane etc. The stem is positively photosensitive and negatively gravitationally bound.

Difference Between monocot and dicot stem

एकबीजपत्री तना	द्विबीजपत्री तना
इसमें कैम्बियम नहीं पाया जाता। फलतः द्वितीयक वृद्धि का अभाव होता है।	इसमें कैम्बियम पाया जाता है, इसलिए द्वितीयक वृद्धि भी पाई जाती है।
मज्जा (pith) अनुपस्थित होता है।	मज्जा उपस्थित होता है।
इसकी एपीडर्मिस पर रोम नहीं पाए जाते।	इसकी एपीडर्मिस पर रोम पाए जाते हैं।
इसकी हाइपोडर्मिस स्क्लेरेन्काइमा की बनी होती हैं।	इसकी हाइपोडर्मिस कोलेन्काइमा की बनी होती है।
इसमें संवहन बण्डल बन्द प्रकार के होते हैं।	इसमें संवहन बण्डल खुलै प्रकार के होते हैं।
इसमें मज्जा किरणे नहीं पाई जाती हैं।	इसमें मज्जा किरणें पाई जाती हैं।

Type of Plant Stem

According to the condition of the land, there are three types of stems which are as follows:

Underground Stem

Underground stem The part of the plant’s stem that is found inside the ground. In the underground stem, festoons, leaf buds and scales are found. Under unfavorable conditions the underground stem becomes thick and fleshy due to food storage.

For example: turmeric, ginger, banana, fern, potato, onion, garlic, kachalu, jimmikand, arbi etc.

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Modifications of underground stem

There are four types of underground stem which are as follows:

(i) Rhizorne:

It is a thick, spreading underground stem. Axillary and anterior buds are also found in it. This stem may be branchless or branched. Sometimes adventitious roots also develop in it. In these clear festivals, festival treaties and skalpatras are found. This type of underground stem is found in plants like turmeric, ginger, banana, fern etc.

(ii) Stem tuber:

It is a type of underground stem. It gets flushed to the top due to food storage. There are many pits on the surface of this type of stem, which are called eyes. Each eye is a scale sheet, which shows the state of the festival and there are dormant buds. Aerial branches emerge from these dormant buds, which have an axillary bud at the front end, which give birth to a new plant by growing in favorable conditions. This type of stem is found in potatoes.

(iii) Bulb:

This type of underground stem is made up of many small scaly leaves. These scales become fleshy due to storage of water and food. The outer layer of this type of underground stem is dry. These stems are found carrying scale sheets arranged in a central order. Onion and Garlic are the best examples of this type of underground stem.

(iv) Corm:

This type of underground body is a condensed form of the rhizome. It grows in an upward direction below the ground. Large amount of food gets stored in it. Buds are found in the orbit of scale leaves, while adventitious roots emerge from its base. This type of underground stem is seen in Kachalu and Jimikand.

Sub Aerial Stem:

When some part of the stem is found inside the ground and some part is found in the air outside the ground, then this type of stem is called semi-aerial stem. Such as – Cow grass, Mercelia, Passiflora, Arui, Hyacinth, Sea soak, Chrysanthemum, Peppermint etc.

Buds are found for vegetative reproduction in semi-aerial stems, from which lateral branches are produced.

Modification of sub aerial stem:

There are four types of hemispherical stem which are as follows:

(i) Runner-

It is a semi-aerial stem spreading parallel to the surface of the land. Long and thin inter nodes are found in this type of stem. The branches and stems grow upwards from the hills and the erectile roots come out inside the ground, the subterranean stem is found in Doob grass, Mercelia etc.

(ii) Stolon:

This type of semi-aerial stem grows in the horizontal direction inside the ground. Internodes and nodes are found on this type of stem. The adventitious roots develop downwards and branches upwards from the mountain joints. This type of semi-anaerobic stem is found in Arui and Passiflora.

(iii) Offset:

This type of semi-pneumatic stem is similar to the runner, but their nodes are thicker and shorter. Above the festivals, the leaves are like a free plant. Hyacinth is a good example of a geostar.

(iv) Suckers:

This type of semiaquatic stem has a lateral branch like a stolon stem, but it grows obliquely upwards and gives rise to a new plant. It is smaller than the stolon. This type of semi-aerial stem is found in chrysanthemum, peppermint etc.

Aerial stem:

When the entire stem is situated above the ground, then such a stem is called aerial stem. In this type of stem, branches, leaves, festivals, festivities, buds, fruits, flowers are all found. Example- Rose, Grapes, Hawthorn, Ruscus, Kokolova etc.

Modification of Aerial Stem:

There are five types of pneumatic stem which are as follows:

(i) Stem thorn:

In this type of stem, the orbital buds are converted into thorns. Leaves, branches and flowers develop on these thorns. Ridge columns are found in plants like lemon, vougainvillea etc.

(ii) Stem tendril:

In this type of stem, the branching bud emerging from the axils of the leaves forms a coiled, filament which helps in the climbing of plants with weak stems. This filament itself is called pillar. Columnar stem is found in grapes and plants of Cucurbitaceae family.

(iii) Phyloclade:

It is a green, flattened and sometimes rounded stem that acts as a leaf. Its leaves are converted into a cotyledonous structure. This conversion prevents water loss from plants. The foliage column develops from a branch with indeterminate growth. Hawthorn (Opuntia) and Casurina (Casurina) are the best examples of foliage column.

(iv) Cladode:

Small, green, cylindrical or flattened branches emerge from the leaf joints of some plants. These types of branches emerge from the axils of the leaves, which themselves are transformed into scaly leaves. Such conversion takes place with the aim of reducing the rate of transpiration in plants. The process of photosynthesis is carried out by the green stem and its branches. This type of transformation of stems is called clade. Asparagus, Ruscus are beautiful examples of Panabhi festival.

(v) Bulbil:

The axillary and flower buds of some plants are modified into special small-sized structures, which are called bulbils. These leaflets separate from their mother plant and fall into the soil and develop under favorable conditions and give birth to new plants. Leaflet is found in plants like Aloe, Agave etc.

Tags: Characteristics of Stem, Stem Definition, Stem Functions, Stem Transformation