Question

Pneumatophores are
A. Negatively geotropic
B. Positively geotropic
C. Negatively phototropic
D. Thigmotropic

Answer 1

Hint: Pneumatophores are modified specifically for the aerial roots stemming from a subterranean root system, which helps the plants to use air in waterlogged soil habitats. Pneumatophores are adventitious roots. The term mangrove is also applied to the thickets and forests of these plants.

Complete answer: Another name of Pneumatophores is called breathing roots. These are available in mangrove trees. These are the changes in the root which develops in a similar direction as that of the shoot. Therefore, they are negatively geotropic as well also positively phototropic.

Additional information: Pneumatophores are modified root structures that develop out from the surface of the water and help in the aeration necessary for root respiration in case of hydrophytic trees such as many of the mangrove species like (e.g., Avicennia germinans and Laguncularia racemosa), bald cypresses, and cotton (tupelo) gum (Nyssa aquatica). Mangrove, any of certain shrubs and trees belonging primarily to the Rhizophoraceae which typically have support roots, i.e., visible support roots. The term mangrove is also applied to the thickets and forests of these plants.

So, the correct answer is Negatively geotropic.

Note: In some plants like Rhizophora which grow in swampy areas, many roots come out of the ground and grow vertically upwards to obtain oxygen, these roots are called pneumatophores. Mangrove, any of certain shrubs and trees belonging especially to the Rhizophoraceae. That grows in thickest forests which includes the tidal estuaries, in mudflats and on muddy shores; and which typically have support roots, i.e., exposed support roots.