Soil supports the plants
to stand upright. Not only that, the soil supplies water to plants. It also
supplies nutrients: compounds of K, N2, P, Mg and other elements.
Some plants (Lithophytic: plants growing on rocks, and epiphytic: plants
growing on other plants-fern, orchids) take nutrients from air as well as from
any waste or debris.
Many plants take oxygen from the atmosphere as
well as from the soil through roots – for respiration. The oxygen is
combined with glucose (made from starch) to give energy to plants.
Underwater plants use the dissolved oxygen. Some vascular plants (mangroves) grow
also with their roots in soil or water without oxygen supply.
Vascular plants have vascular vessels to transport food and water to all parts
of the plant including stem, roots, and leaves. These are called conducting
tissues to carry water and nutrients.
Some plants (carnivorous) also eat insects in addition to the other nutrients