Tag: root - external morphology

Moniliform or beaded roots are adventitious roots which are swollen at regular intervals like beads of a necklace. For example, Baseila rubra (India spinach), Momordica and some grasses.

Dionaea is an example of fresh water, rootless insectivorous plant. Dionaea, is a carnivorous plant native to subtropical wetlands. It catches its prey, chiefly insects and arachnids, with a trapping structure formed by the terminal portion of each of the plant's leaves and is triggered by tiny hairs on their inner surfaces. When an insect or spider crawling along the leaves contacts a hair, the trap closes if a different hair is contacted within twenty seconds of the first strike. The requirement of redundant triggering in this mechanism serves as a safeguard against a waste of energy in trapping objects with no nutritional value.

Raphanus sativus is an edible root vegetable of the Brassicaceae family. It has a fusiform taproot system. The edible part of radish is a modified tap root. Radishes are eaten as a salad vegetable. 

Growth of tap roots is towards gravity. Typically, a taproot is very thick. It is tapering in shape and grows directly downward into the soil towards the force of gravity. In plants with taproot systems, the taproot is the central root from which other roots sprout laterally.
Thus, the correct answer is option A.

The drug belladona is obtained from roots of Atropa belladona. Atropa belladonna, commonly known as belladonna or deadly nightshade, is a perennial herbaceous plant in the family Solanaceae. The foliage and berries are extremely toxic, containing tropane alkaloids. These toxins include scopolamine and hyoscyamine, which cause a bizarre delirium and hallucinations.

Dicot root shows secondary growth in thickness. Dicot root possess 2-4 xylem and phloem patches. These patches are separated by parenchymatous cells. The parenchymatous tissue present in between xylem and phloem become meristematic in later stages. These are called as cambium ring. 

Plant roots are so designed that it can take up water and nutrients from the soil and pass it on to the shoot. At the same time, there are chances of  unwanted and toxic compounds be also taken along with any soilborne pathogens. To protect the roots from such intake, specific unicellular tissues, such as exodermis is located at the outer surface of the root directly below the root epidermis.
Thus, the correct answer is option C.

Screwpine shows stilt roots because the stem of the plant is weak and needs additional support to withhold the erect structure by arising roots from the lower nodes.

Banyan Trees are having a supporting root system for its branches. But maize and sugarcane have the stilt root to help the plant to stand erect. Prop roots or columnar roots in banyan. These aerial roots appear like props or columns. 

In banyan tree, these roots develop from the large, horizontal branches of large trees. Stilt roots in maize and Sugarcane are adventitious. They are developed from the lower part of the stem and grow obliquely. The stilt roots give additional support to the plants.

The correct options are i and ii.

Thus the correct option is D.