Question

In herbaceous plants having thin soft leaves, the rate of cuticular transpiration is found to be:
A. 10% of the total transpiration.
B. 30% of the total transpiration.
C. 50% of the total transpiration.
D. 70% of the total transpiration.

Answer 1

Herbaceous plants, which include many perennials and virtually all annuals and biennials, are vascular plants with no permanent woody stems above ground. Graminoids, forbes, and ferns are examples of herbaceous plants.

Complete answer:
Transpiration is the loss of water in the form of vapour from a plant's exposed portions. The amount of water lost through transpiration is fairly significant – 2 litres. In fact, a plant loses 98-99 percent of the water it absorbs through transpiration. Only around 0.2 percent is utilised in photosynthesis, with the rest staying in the plant during its development.
Cuticular Transpiration: The cuticle or epidermal cells of the leaves and other exposed portions of the plant are affected. Cuticular transpiration accounts for only 3-10% of total transpiration in most terrestrial plants. Cuticular transpiration can account for up to 50% of total transpiration in herbaceous shade-loving plants with a thin cuticle. Cuticular transpiration occurs at all times of the day and night.
Other type of transpiration are as follows:
The most significant form of transpiration is stomatal transpiration. Stomatal transpiration accounts for between 50 and 97 percent of total transpiration. It happens because of the stomata. Stomata are primarily found on the leaves. They can be found on young stems, blooms, and fruits. The stomata allow the plant's moist core to be exposed to the air.
Lenticular or Lenticellata Transpiration: This kind of respiration is only seen in the wooden branches of trees that have lenticels. Lenticular transpiration accounts for just 0.1% of overall transpiration. However, because lenticels lack a closing mechanism, it continues throughout all hours of the day and night.
Transpiration through the corky coating of the stems is known as bark transpiration. Because of the greater area, bark transpiration is typically measured to be higher than lenticular transpiration. Bark transpiration, like cuticular and lenticular kinds of transpiration, occurs constantly during the day and night.

So, option C is the right answer.

Note: Water inside the exposed portions of the plant requires a source of heat energy in order to produce vapours. During the day, it is radiant energy, and at night, it is heat energy from the transpiring organ. The temperature of the transpiring organs falls 2-5°C below that of the atmosphere in both instances.