Question

Phyllotaxy is the arrangement of
A)Leaflets
B)Leaves
C)Stipules
D)Branches

Answer 1

Hint: Some early scientists made observations of the spiral arrangements of plants, especially Leonardo da Vinci. Charles Bonnet noted in 1754 that in both the clockwise and counter-clockwise golden ratio sequences, the spiral phyllotaxis of plants was commonly articulated.

Complete answer:
The leaf arrangements are phyllotaxy on the plant's stem. A structure similar to a leaf is the leaflet. Together, the compound leaf produces many leaflets. Stipules are leaf-like structures found at the base of the petiole. The simple arrangements of leaves on a stem are opposite and alternating (also known as spiral). If several leaves appear, or seem to occur, leaves may also be whorled from the same point (at the same node) on a stem.

Veronicastrum virginicum has whorls of long internodes dividing the leaves. For an opposite leaf arrangement, at the same position (at the same node), on opposite sides of the stem, two leaves emerge from the stem. It is possible to conceive of an opposite leaf pair as a whorl of two leaves. Each leaf appears at a different point (node) on the stem with an alternative (spiral) pattern.

Hence, the correct answer is option (B)

Note: Ultimately, local degradation of the plant hormone auxin in some parts of the meristem regulates the pattern of leaves on a plant. In localized areas in which auxin is absent, leaves are initiated. Auxin continues to flow toward it as a leaf is initiated and starts growth, thereby depleting auxin from another region on the meristem where a new leaf is to be initiated.