(i) Potato is a stem and sweet potato is a root:
(a) Potato are stem tubers because they are fleshy,swollen, rounded or oblong distal portions of underground axillary or adventitious branches.These branches arise from the underground basal nodes of the aerial shoots. The tips of these branches become enlarged in the form of tubers, due to accumulation of surplus food material manufactured by the aerial shoots.
(b) Sweet potato is a root tuber because these are adventitious roots that become thick and fleshy due to storage of food and are swollen without any definite shape. The root tubers of sweet potato also bear adventitious buds from which new plants can develop.
(ii) Flower is a modified shoot:
(a) A flower arises from a bud like the vegetative branch.
(b) The thalamus of a flower represents a condensed axis in which the intemode remains suppressed.
(c) The floral leaves are borne on the thalamus just like stem.
(d) There is a striking similarity of sepals and petals to leaves with regards to structure, form and venation.