Which plant shows a cylindrical phylloclade?

• A. Opuntia
• B. Neem
• C. Silk cotton
• D. Euphorbia

Answer: (D)

Phylloclade is a stem that takes over the leaf's role in photosynthesis, often becoming a reduced or specialized, leaf-like structure. When a plant has cylindrical, pencil‑like stems that perform photosynthesis, that is a classic form of a cylindrical phylloclade. Euphorbia includes many species with slender, cylindrical stems (like the pencil cactus), which are the photosynthetic organs in place of true leaves. The other plants here don’t show this cylindrical stem adaptation: Neem and silk cotton have normal leaves and stems, and Opuntia has flat, paddle-shaped stems (cladodes) rather than cylindrical ones. So, the plant with cylindrical phylloclades is Euphorbia.