The flattened, green, leaf-like stem of Opuntia that carries out photosynthesis is called a
- A.Phyllode
- B.Phylloclade
- C.Cladode
- D.Pulvinus
Correct answer
Explanation
The correct answer is B, a phylloclade. In Opuntia and in many Euphorbia species the leaves are reduced to spines to cut down transpiration, and the stem takes over photosynthesis by becoming flattened, green and fleshy; such a stem is a phylloclade. A is wrong because a phyllode is a modified leaf, specifically a flattened green petiole, as in the Australian acacia, where the lamina falls early. C is wrong in the strict sense expected here: a cladode is a phylloclade of only one or two internodes and is usually cylindrical, as in Asparagus and Casuarina, so it is the narrower term, not the one for Opuntia. D is wrong because the pulvinus is the swollen leaf base found in legumes, a part of the leaf and not a photosynthetic stem.
Read the full article: Morphology of Flowering Plants: Root, Stem and Flower
Practice Questions
View allWhich of the following plants can survive in extremely saline conditions?
- A.Epiphytes
- B.Halophytes
- C.Xerophytes
- D.Hydrophytes
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Halophytes are plants of saline soils, chiefly the mangroves of tidal creeks and deltas such as Rhizophora and Avicennia, and their morphology is shaped by that habitat: they bear pneumatophores, negatively geotropic breathing roots that rise out of the waterlogged mud, along with stilt and prop roots for support and…
Read the full explanation →The potato is a modification of which plant organ?
- A.Root
- B.Stem
- C.Leaf
- D.Fruit
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The potato is an underground stem tuber, the swollen tip of an underground branch, and the proof is in its morphology: it bears nodes, the depressions called eyes, and each eye carries an axillary bud that can sprout into a new shoot.
Read the full explanation →The edible part of the carrot is a modified
- A.Conical taproot
- B.Fibrous root
- C.Stem tuber
- D.Adventitious root
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The carrot stores food in its primary root, which is broad at the top and tapers steadily to a point, and that shape is described as conical.
Read the full explanation →Prop roots, which hang from spreading branches and give them mechanical support, are a familiar feature of which tree?
- A.Maize
- B.Banyan
- C.Screw pine
- D.Rhizophora
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The banyan's horizontal branches grow so long and heavy that they send down thick aerial roots which reach the soil, thicken into pillars and carry the weight of the branch; these are called prop or pillar roots.
Read the full explanation →Pneumatophores, the negatively geotropic breathing roots, are characteristic of
- A.Mangrove plants such as Rhizophora
- B.Desert plants such as Opuntia
- C.Epiphytic orchids such as Vanda
- D.Parasitic plants such as Cuscuta
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The mud of a tidal swamp is waterlogged and almost free of oxygen, so these plants send up roots that grow vertically out of the soil into the air and take in oxygen through pores; such roots grow against gravity and are therefore called negatively geotropic.
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