Question

Cuscuta is a
A. Total root parasite
B. Total stem parasite
C. Partial stem parasite
D. Epiphyte

Answer 1

Hint:- Cuscuta is a genus of nearly more than two hundred species of plants belonging to the genus Convolvulaceae. This genus is found throughout the temperate as well as tropical regions of the world. It shows the greater diversity in the subtropical and tropical regions of the world. However, the genus is rare in the cool climates of the temperate regions and only four species are found.

Complete step-by-step solution:- Cuscuta is a yellow or orange colored plant that is parasitic in nature. It is also known as dodder. It is a parasitic plant and can be identified by the thin stems which are devoid of leaves. Leaves are reduced into minute scales and do not contain chlorophyll. Some species of Cuscuta are able to perform photosynthesis at a very minimal rate but most of them cannot perform the photosynthetic process. It depends entirely on the host plant for its nutrition.
The dodder plant attaches itself with the host plant and wraps itself around the host plant. If the food produced by the host plant is beneficial to the Cucuta plant, it enters its sucking apparatus which is known as the haustoria, into the host plant. After the process of attaching to the host plant, the root of the Cuscuta plant, if any dies and the plant now derives nutrition from the host plant. The only vegetative part of the Cuscuta plant is the stem and it is considered as a total stem parasite.
The Cuscuta plant covers the whole of the host plant and by inserting the haustoria it establishes a connection with the vascular bundles of the host. This connection helps the dodder plant to obtain water, carbohydrates and other important solutes.
The seeds produced by Cuscuta are minute and are produced in large quantities. These seeds are hard coated and can survive depending upon the environmental conditions. The seeds after germination must find and infect a suitable host otherwise the seeds will perish. The seeds contain food reserves which are the only sources of food for the germinating seeds.
Therefore, the correct option is option B.

Note:- Cuscuta is an obligate stem holoparasite which affects a large number of other plants known as the host plants. The dodder plant forms connection with the host plant and derives all the required nourishment from the host plant. It bears reduced leaves with little or no chlorophyll and no roots. The only functional part of the plant is the stem. Cuscuta is referred to as a total stem parasite plant.