Aerial stem modifications are modifications to the aerial stems, vegetative

buds In botany, a bud is an undeveloped or Plant embryogenesis, embryonic Shoot (botany), shoot and normally occurs in the axil of a leaf or at the tip of a Plant stem, stem. Once formed, a bud may remain for some time in a dormancy, dormant conditi ...

and floral buds of plants growing in different conditions and which perform functions such as climbing, protection, support, synthesis of food, or vegetative propagation. Aerial stem structures that undergo modifications to perform these special functions include tendrils, thorns, hooks,

phylloclade Phylloclades and cladodes are flattened, photosynthetic shoots, which are usually considered to be modified branches. The two terms are used either differently or interchangeably by different authors. '' Phyllocladus'', a genus of conifer, is na ...

, tuberous stems, and bulbils. The auxiliary or the terminal part of the modified structures shows their stem nature.

Tendrils

Some weak-stemmed plants produce wiry, coiled, sensitive, and delicate organs for climbing. They are called tendrils. These may develop from either the axillary bud or the terminal bud of the stem. In '' Passiflora'', the tendrils develop from the axillary bud. In '' Cissus quadrangularis'' and in ''

Vitis vinifera ''Vitis vinifera'', the common grape vine, is a species of flowering plant, native to the Mediterranean Basin, Mediterranean region, Central Europe, and southwestern Asia, from Morocco and Portugal north to southern Germany and east to northern ...

'', the terminal bud develops into tendrils.

Thorns

These are hard, woody, pointed structures meant for protection. They are provided with

vascular tissue Vascular tissue is a complex transporting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem. These two tissues transport fluid and nutrients internally. T ...

, which may develop from the axillary bud or terminal buds. They control

transpiration Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. It is a passive process that requires no energy expense by the plant. Transpiration also cools plants, c ...

by reducing the vegetative growth. In ''

Bougainvillea ''Bougainvillea'' ( , ) is a genus of thorny ornamental vines, bushes, and trees belonging to the family, Nyctaginaceae. They are native to Brazil, Bolivia, Paraguay, Peru, and Argentina. There are between 4 and 22 species in the genus. The i ...

'', ''

Punica granatum The pomegranate (''Punica granatum'') is a fruit-bearing deciduous shrub in the family Lythraceae, subfamily Punicoideae, that grows between tall. Rich in symbolic and mythological associations in many cultures, it is thought to have originat ...

'', and '' Duranta'', the

axillary bud The axillary bud (or lateral bud) is an Plant embryogenesis, embryonic or Organogenesis#Plant organogenesis, organogenic Shoot (botany), shoot located in the axil of a leaf. Each bud has the potential to form shoots, and may be specialized in prod ...

develop into thorns. In ''Duranta'', the thorns are provided with leaves and flowers. In ''

'', the thorns bear leaves and branches. In '' Carissa carandas'', the terminal bud produces a pair of thorns. They help in protection.

Bulbils

When the axillary bud becomes fleshy and rounded due to the storage of food, it is called a

bulb In botany, a bulb is a short underground stem with fleshy leaves or leaf basesBell, A.D. 1997. ''Plant form: an illustrated guide to flowering plant morphology''. Oxford University Press, Oxford, U.K. that function as food storage organs duri ...

. It gets detached from the plant, falls on the ground, and develops into a new plant. e.g. '' Dioscorea''. It is in the axil (the space between the leaf and stem).

Cladode

These are green branches of limited growth (usually one internode long) that have taken up the functions of photosynthesis. True leaves are reduced to scales or spines, e.g. ''

Asparagus Asparagus (''Asparagus officinalis'') is a perennial flowering plant species in the genus ''Asparagus (genus), Asparagus'' native to Eurasia. Widely cultivated as a vegetable crop, its young shoots are used as a spring vegetable. Description ...

''.

References

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