Question

Desmodium, ‘Indian telegraph plant’ belongs to the family
A) Liliaceae
B) Papilionaceae
C) Malvaceae
D) Solanaceae

Answer 1

Hint: Telegraph Plant is known for its tiny lateral leaflet movement at rates that are swift enough to be experienced by the naked eye. This is a method for controlling the sun to optimize sunshine.

Complete Answer:
First we should know about the Desomodium to answer this question. Desmodium gyrans is an Asian herb of tropical origin. Since the movement of leaves that mimic the semanphore telegraph signals, it is generally known as Telegraph plant or Dancing grass or Semaphore fruit. Semaphore is a telegraph signal device in which information is communicated by visual signals such as rods, flags, etc. at a distance.

Now, let us find the solution from the options-
- Any plants display random vibrations of their leaflets to and fro.
-In several species, certain movements are found. Generally, temperature, contact, sunlight, humidity, chemicals, etc. are guided by them.
-Desmodium, sometimes referred to as the Indian telegraph vine, comprises two terminal and lateral leaflets.
- Desmodium leaflets oscillate autonomously, depending on the temperature.
-The rhythmic swelling and shrinking of motor cells found in the pulvinus leaflet base was assumed to be due to such oscillations. This leaflet movement is analogous to telegraphic signals.
-It is, thus, often called the Indian telegraph factory. Desmodium, the Indian telegraph vine, has legumes, brightly coloured papilionaceous flowers and belongs to the Papilionaceae family.

Thus, the correct answer is option (B) Papilionaceae.

Note: Due to its unusual leaflet movements, the telegraph plant has aroused a lot of interest between plant physiologists. The lateral leaflets show rhythmic up and down motions in the minute scale, while the terminal leaflets shift from a horizontal direction during the day and down during the night.