Biology · Morphology of Flowering Plants · NEET
Potato is a modified STEM, not a root. It is a stem tuber. Proof: it has nodes (the 'eyes'), and each eye has an axillary bud that can grow into a new shoot. Roots never have nodes or buds. This is why potato reproduces vegetatively. Do not confuse it with sweet potato, which is a modified adventitious ROOT.
Both are underground stems, but a rhizome grows horizontally and is thick with visible nodes, internodes and scale leaves (examples: ginger, turmeric, banana). A tuber is a swollen tip of an underground branch that stores food and shows 'eyes' (nodes with buds), like potato. In short: rhizome is a horizontal underground stem; tuber is the swollen storage tip of a stem branch.
Yes. A runner is a sub-aerial stem that creeps horizontally along the ground. In grass and strawberry, runners grow out from the base, root at the nodes, and grow new plants. This is vegetative propagation. NEET 2022 confirmed statement (e): sub-aerial stems in grasses and strawberry help in vegetative propagation.
They are STEM modifications. Thorns are modified axillary buds, so they are woody, hard and pointed and used for protection and climbing. This is a very common NEET trap. NEET 2017 asked exactly this for Bougainvillea and the answer is stem. A common wrong option is 'leaf' or 'leaflet' — that is incorrect for Citrus and Bougainvillea.
A phylloclade is an aerial stem that becomes flat (or cylindrical), green and fleshy to do photosynthesis when leaves are reduced or absent. The classic example is Opuntia (a cactus), where the flat green pads are stems, and the leaves are reduced to spines. NEET 2016 asked this: flat green stems doing the work of leaves = phylloclade.
All four are sub-aerial stems used for vegetative propagation. Runner creeps flat on the soil (grass, strawberry). Stolon is a slender lateral branch that arches and touches the ground (jasmine, mint). Sucker grows from an underground base, then comes up (mint, Chrysanthemum, banana). Offset is a short thick horizontal branch in aquatic plants (Pistia, Eichhornia).
Identify the correct set of statements: (a) The leaflets are modified into pointed hard thorns in Citrus and Bougainvillea (b) Axillary buds form slender and spirally coiled tendrils in cucumber and pumpkin (c) Stem is flattened and fleshy in Opuntia and modified to perform the function of leaves (d) Rhizophora shows vertically upward growing roots that help to get oxygen for respiration (e) Sub-aerially growing stems in grasses and strawberry help in vegetative propagation.
In Bougainvillea thorns are the modifications of:
Stems modified into flat green organs performing the functions of leaves are known as:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Because the same examples (potato, ginger, strawberry, Opuntia, Citrus) keep appearing and students confuse stem with leaf or root. Learning which organ is modified gives you easy marks in Morphology of Flowering Plants.
Ginger is an underground STEM called a rhizome. It grows horizontally, has nodes, internodes and scale leaves, and stores food. Turmeric and banana rhizomes work the same way.
The sub-aerial stems: runner, stolon, sucker and offset. They grow new plants at their nodes. Underground stems like potato, ginger and Colocasia also help in vegetative propagation.
A stem tendril is a slender, spirally coiled stem branch used for climbing (cucumber, pumpkin, grapevine). A stem thorn is a hard pointed stem used for protection (Citrus, Bougainvillea). Both come from axillary buds.
The flat green pad of Opuntia is a modified STEM called a phylloclade. It does photosynthesis because the true leaves are reduced to spines to save water.
