Question

Match the stem modifications in column I with their appropriate examples in column II:

Column I	Column II
A. Underground stem	I. Euphorbia
B. Stem tendril	II. Opuntia
C. Stem thorn	III. Potato
D. Flattened stem	IV. Citrus
E. Fleshy cylindrical stem	V. Cucumber

• A. A-I, B-II, C-III, D-V, E-IV
• B. A-II, B-III, C-IV, D-V, E-I
• C. A-III, B-IV, C-V, D I, E-II
• D. A-III, B-V, C-IV, D-II, E-I

Answer 1

The correct option is D A-III, B-V, C-IV, D-II, E-I

Stem is the part of the plant that grows generally above the ground. Stems in some plants may undergo certain modifications to meet certain requirements.

Column I displays different stem modifications. Stem modifications can be of three main types: Underground, sub-aerial and aerial stem modifications.

Underground stem modifications include rhizomes, tuber, corm and bulb. These become swollen to store food. E.g. Potato.

Sub-aerial stem modifications include runners, stolon, offset and suckers.

Aerial stem modifications include stem tendrils, thorn and phylloclade. Stem tendrils are found in plants with weak stems. It is formed when axillary bud modifies to form green, thread-like sensitive structures with adhesive glands for fixation. E.g. Gourds (pumpkins, cucumbers, watermelons) and grapevines. They are stiff, pointed structures produced by modification of axillary buds. E.g. Citrus and Bougainvillea.

Phylloclade is a stem modified into a flat, fleshy and green leaf like structure. It carries out photosynthesis like leaves. E.g. They are thick, fleshy and succulent in Opuntia and cylindrical in Euphorbia and Casuarina.