Multiple Choice Questions (MCQs): The Flower - NEET MCQ

There are three forms of thalamus in regard to the insertion of pistil and androperianth or other floral organs..
(i) Hpogyny - When the sepals, petals and stamens are successively and separately inserted below the ovary in the flowers, the condition is known to be hypogyny and the ovary is said to be ruperious. Such flowers are called hypogyous as in mustard,china rose and brinjal.
(ii) Epigyny - When the sepals, petals and stamens are successively and separately inserted above the ovary in the flower, the condition is descried as epigymy. The ovary in this situation is said to be inferior. Such flowers are termed epigynous, e.g., guave, cucumber.
(iii) perigymy - When the sepals, petals and stamens are inserted at the same plane as the ovary, the condition is known as perigyny. The ovary in such condition is half superior, sub-inferior or partially inderior ovary. Such flowers are called perigynous, e.g., rose, pea.
Topic in NCERT: THE FLOWER
Line in NCERT: "Based on the position of calyx, corolla and androecium in respect of the ovary on thalamus, the flowers are described as hypogynous, perigynous and epigynous."

When stamens are attached to the perianth, they are known as epiphyllous, e.g., Asparagus, lily.

Topic in NCERT: Androecium

Line in NCERT: "When stamens are attached to the petals, they are epipetalous as in brinjal, or epiphyllous when attached to the perianth as in the flowers of lily."

In hypogynous condition of flowers, the thalamus is convex or conical. Gynoecium occupies the topmost (superior) position at the thalamus and other parts of flower are borne successively below. Androperianth or other floral organs are inferior, e.g, Hibiscus rosa sinensis, Ranunculus, etc.

Topic in NCERT: Position of floral parts on thalamus

Line in NCERT: "In the hypogynous flower the gynoecium occupies the highest position while the other parts are situated below it."

The arrangement of ovules within the ovary is known as placentation. The placentation are of different type namely, marginal, axile, parietal, basal, central and free central. In marginal placemation the placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows, e.g. pea. When the placenta is axial and the ovules are attached to it in a multilocular ovary, the placentation is saidd to be axile, e.g., China rose, tomato and lemon In parietal placentation, the ovules develop on the inner wall of the ovary or on peripheral part. Ovary is one -chambered but it becomes two chambered due to the formation of false septum, e.g., mustard. When the ovules are borne on central axis and septa are absent, as in Primrose, the placentation is called free central In basal placentation, the placenta develops at the base of obary and a single ovule is attached to it, e.g., sunflower, marigold.

Topic in NCERT: Placentation

Line in NCERT: "Placentation: The arrangement of ovules within the ovary is known as placentation. The placentation are of different types namely, marginal, axile, parietal, basal, central and free central (Figure 5.12)."

In perigynous condition of a filower, the gynoecium is situated in the centre and other floral parts are located on the rim of the thalamus almost at the same level. Ovary is said to be half-inferior, e g. Rosa (Flask-shaped thalamus) Prunus (Cup-shaped thalamus).
Topic in NCERT: Position of floral parts on thalamus
Line in NCERT: "In the hypogynous flower the gynoecium occupies the highest position while the other parts are situated below it. The ovary in such flowers is said to be superior, e.g., mustard, china rose and brinjal. If gynoecium is situated in the centre and other parts of the flower are located on the rim of the thalamus almost at the same level, it is called perigynous. The ovary here is said to be half inferior, e.g., plum, rose, peach."

Option (a) represents placentation as seen in China rose. It is axile type of placentation, which occurs in syncarpous pistils. Ovary is partitioned into 2 or more chambers. Placentae occur in the central region where the septa meet so that an axile column bearing ovules is formed. In China rose, ovary is pentalocular.

Topic in NCERT: placentation

Line in NCERT: "When the placenta is axial and the ovules are attached to it in a multilocular ovary, the placentation is said to be axile, as in china rose, tomato and lemon."

In papilionaceous corolla , five unequal petals are arranged like a butterfly. The posterior large bilobed petal is called standard or vexillum and it overlaps two smaller lateral petals called wings/alae. The latter in turn overlap the two anterior petals which are fused by the upper anterior margins to form a boat-shaped structure called keel or carina.
Topic in NCERT: Aestivation
Line in NCERT: "In pea and bean flowers, there are five petals, the largest (standard) overlaps the two lateral petals (wings) which in turn overlap the two smallest anterior petals (keel); this type of aestivation is known as vexillary or papilionaceous."

In valvate aestivation, sepals or petals in a whorl just touch one another at the margins without overlapping. This type of aestivation can be observed in the flowers of Calotropis.

• Valvate Aestivation: Sepals or petals in a whorl touch at the edges but do not overlap.
• Example: Calotropis exhibits valvate aestivation.

Thus, the correct answer is:
A: valvate, Calotropis
Topic in NCERT: Aestivation
Line in NCERT: "When sepals or petals in a whorl just touch one another at the margin, without overlapping, as in Calotropis, it is said to be valvate."

In vexillary/descending imbricate aestivation, the posterior petal overlaps the two lateral petals and the latter overlap the two anterior petals. It is also called papilionaceous corolla and found in members of family Papilionaceae.

Topic in NCERT: Aestivation

Line in NCERT: "In pea and bean flowers, there are five petals, the largest (standard) overlaps the two lateral petals (wings) which in turn overlap the two smallest anterior petals (keel); this type of aestivation is known as vexillary or papilionaceous."

Topic in NCERT: Aestivation
Line in NCERT: "Aestivation: The mode of arrangement of sepals or petals in floral bud with respect to the other members of the same whorl is known as aestivation. The main types of aestivation are valvate, twisted, imbricate and vexillary."