Question

Study the following statements and select the correct option.
(a) Buds are present in the axil of the leaflets of the compound leaf.
(b) Pulvinus leaf-base is present in some leguminous plants.
(c) In alstonia, the petioles expand, become green and synthesize food.
(d) Opposite phyllotaxy is seen in guava.
(A) (b) and (d)
(B) (a) and (c)
(C) (b)and (c)
(D) (a) and (b)

Answer 1

In botany, the arrangement of leaves on a plant stem is known as phyllotaxis or phyllotaxy. In nature, phyllotactic spirals form a variety of patterns. In both simple and compound leaves, a bud is present in the petiole axil, but not in the leaflet axil of the compound leaf. The petioles in Australian Acacia extend, turn green and produce food.

Complete answer:
A swelling is known as pulvinus at the base of a petiole. It is a joint-like thickening of a leaflet at the root. It enables movement that is independent of development. A pea and a gramme, for example. Two leaves emerge from the stem at the same stage and at the same node. But this occurs on opposite sides of the stem, in an opposite leaf arrangement. For instance, guava. In both simple and compound leaves, a bud is present in the axil of the petiole but not in the axil of the leaflets of the compound leaf. The leaves of the Australian acacia are thin and short-lived. The petioles are dilated and green and food is synthesised by them.
Pulvinus, in some plants, is a mass of thin-walled cells at the base of the leaf petiole, creating a swollen region around the vascular tissue. The pulvinus in TURGOR is subject to substantial alterations. The pulvinus, for example, is turgid throughout the day in the runner bean and supports the petiole, so that the leaf is held outwards. The pulvinal cells lose turgidity at night, and the leaf droops. Such daytime leaf positions are often referred to as sleep movements.

So, the correct answer is ‘(b) and (d)’.

Note:
Changes in turgor pressure leading to contraction or expansion of the parenchyma tissue are caused by pulvinar motion. When sucrose is unloaded into the apoplast from the phloem, the reaction is initiated. The increased concentration of sugar in the apoplast reduces the potential of water and causes the efflux of potassium ions from the cells around it.