Question

Assimilatory (photosynthetic) roots are a characteristic of
1) Trapa and Tinospora
2) Taeniophyllum
3) Both A and B
4) None of these

Answer 1

Hint: Adventitious roots are modified to perform photosynthesis in plants like orchids, gilo, etc.

Complete solution:
It is the beauty of the structures of plants that these can be modified to perform a range of functions, like stem can be modified to perform storage as in potato and roots can be modified to perform photosynthesis in plants like Tinospora (gilo), orchids, Taeniophyllum, Trapa, and Podostemon.
So, what types of roots are assimilatory roots. Well, these are modified adventitious roots, which when exposed to the sun, turn green and photosynthetic in function. They appear like green threads hanging from the plant. Their name is based on the function performed by them, that is, the assimilation of food.
The assimilatory roots are present in the diversity of habitats. These can be found in terrestrial plants, aquatic plants and epiphytes like orchids. They grow horizontally in response to gravity, so they are also called diageotropic.
They show a peculiar branching pattern, so they are referred to as plagiotropic. They perform gaseous exchange through their general surface.

Note: Roots can be modified for a variety of functions such as:
1) Modified tap roots for storage as seen in turnip and sweet potato
2) Modified tap roots for respiration, called the pneumatophores, as seen in halophytes.
3) Nodulated roots for nitrogen fixation, as seen in family Fabaceae.
4) Adventitious roots modified for storage as seen in Dahlia.
5) Moniliform roots for storage as seen in grasses.
6) Modification of adventitious roots for support, like prop roots and stilt roots, as seen in banyan and sugarcane respectively.
7 Climbing roots as seen in a money plant.
8) Buttress roots as seen in Ficus.
9) Parasitic roots as seen in Cuscuta.