Morphology of Flowering Plants Test -6

The mature seeds of plants do not possess endosperm because, it gets used up by the developing embryo during seed development.

In monocotyledonous seeds single cotyledon is called as scutellum. It is found in cereal grains like rice, wheat, maize and other monocots.

When a flower is divided into two equal radial halves in any radial plane passing through the centre, it is said to be actinomorphic. e.g., mustard, datura, chilli.

When more than one carpel is present, they may be free, it is called apocarpous.

Placenta is the parenchymatous cushion present inside the ovary, ovules are borne. Ovules are attached with ovary at placenta to get nourishment.

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 the false septum, e.g., mustard and Argemone.

In the hypogynousflower, thegynoecium occupies the highest position while the other parts are situatedbelow it. The ovary in such flowers is said to be superior.

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.

The stamens in a flower may either remain free (polyandrous) or may be united in varying degrees.

Drupe is an indehiscent fruit in which an outer fleshy part and surrounds a shell of hardened endocarp with a seed. Mango is an example of drupe.

Pneumatophores are the aerial adventitious roots which are conical in shape and filled with air. It enables the plant to breathe air in habitats that have waterlogged soil. Roots may grow down from the stem or up from typical roots. For example, Mangrove family of plants.

Adventitious roots do not arise from the radical of the seed. Instead, they can originate from the plumule parts such as stem, branches, leaves. Hence, they are termed as adventitious roots. Prop roots are the modified roots that give mechanical support to the aerial branches. The lateral branches grow vertically downward into the soil and act as pillars. For example, banyan tree. Pneumatophores are specialized aerial roots that enable plants to breathe air in habitats that have waterlogged soil. The roots may grow down from the stem or up from typical roots. For example, mangrove family of plants (Rhizophoraceae).

Solution

Correct answer is option C.

Explanation for correct option:

• Nepenthes is a tropical pitcher plant or a genus of carnivorous plants in the family Nepenthaceae.
• Nepenthes consist of a climbing stem, a tendril that helps in climbing and protrudes from the tip of the leaf.
• At the end of the tendril, the leaf is modified to form a pitcher which contains a fluid used to catch the prey.

Avicennia is among the most salt-tolerant mangroves. The spreading root system provides stability in shifting substrates. The vertical roots called as pneumatophores project from the mud. These are used in gas exchange as there is very little oxygen available in the mud.

• The corm is a short underground storage organ of the plant. It is a swollen stem that stores food to survive winter, summer drought, and heat. It is also called a bulbotuber. It is covered with scale leaves or tunics. It is seen in plants like Amorphophallus, Colocasia, Corcus. 
• A corm consists of one or more internodes. Internally, a corm consists of parenchyma cells rich in starch. Corm, bulb, tuber, rhizomes are used for vegetative propagation.

Pandanus has stilt roots with very large conspicuous aerial root cap. These are the largest and multiple persistent root caps.

Modified stems are derived from stem tissue that exists under the soil surface. Various modified stems are tuber, bulb, corm, stolon and rhizome. Tuber is a thickened part of a stem which grows underground. Tubers have bud from which a new plant can arise by vegetative propagation. Potato is a modified stem called a tuber. It stores a large amount of edible starch which is used as food.

Artabotrys hexapetalus is found in the tropical climate and is known as "climbing ylang-ylang," an ornamental liana or woody climber. It climbs with hooks formed by the inflorescences. The pedicel develops into hooks for climbing.

Euphorbia looks like a perfect ball, thornless and extremely decorative. It is also known as baseball plant due to its shape. Euphorbia is a subtropical succulent species of Euphorbia genus. They contain water reservoirs for periods of drought. In these plants, stem performs photosynthesis.

The underground stem of a banana plant is called as a rhizome. The terminal growing point of the rhizome is the apical meristem, which is a flattened dome like structure. The leaves and the inflorescence are formed from this apical meristem. Sucker is a lateral shoot that develops from the rhizome and develops into a new banana plant.