(i) Underground parts of a plant are not always roots. Sometimes stem or stem branches occur underground to perform some special functions. For example, potato tuber is a modified stem which is underground. A close observation of potato tuber shows presence of nodes and intemodes and presence of scale leaves and buds at the nodes. Presence of an apical bud at the tip of potato tuber confirms that it is a stem.
(ii) Flower is a modified shoot consisting of a highly reduced stem branch to form thalamus in which the nodes are borne only towards the tip. The floral parts, i.e., sepals, petals, stamens and carpels are arranged in their respective whorls and arise from nodes. The growing point of floral bud is used up in the production of floral organs.
