difference between underground stem and underground root
Stems and roots have very different structures.
Underground stems have structures which you would expect to see in stems growing above ground, e.g. buds. These stems might also turn green when exposed to light as they generate chlorophyll. A good example of an underground stem is the part of the potato plant you eat. The 'eyes' are buds which will sprout. Leave a potao out in the light and it will go green. Several plants use underground stems as storage organs, many (especially grasses) use them to spread, for example couch grass; new plantlets emerge from the buds.
Stems are not specialised for water absorption as roots are and root structures reflect this. There are no buds on roots and they do not go green when exposed to light. Many plants do use roots as storage organs, e.g. carrot, dandelion, etc.
Underground stems have structures which you would expect to see in stems growing above ground, e.g. buds. These stems might also turn green when exposed to light as they generate chlorophyll. A good example of an underground stem is the part of the potato plant you eat. The 'eyes' are buds which will sprout. Leave a potao out in the light and it will go green. Several plants use underground stems as storage organs, many (especially grasses) use them to spread, for example couch grass; new plantlets emerge from the buds.
Stems are not specialised for water absorption as roots are and root structures reflect this. There are no buds on roots and they do not go green when exposed to light. Many plants do use roots as storage organs, e.g. carrot, dandelion, etc.