Plant Nutrient Acquisition: Bryophyte and Cormophyte Strategies

Bryophyte Nutrition

Bryophytes have no true tissues or organs such as roots, stems, or leaves. Nutrients pass directly from cell to cell by diffusion or active transport. Bryophytes require permanently moist environments for transport. Their structure is not equivalent to higher plants; mosses and liverworts have a false root, or rhizoid, which serves only for attachment, and leaf-like structures where photosynthesis occurs. They do not possess true stems, and their cells lack lignin, meaning the plant has no conducting or support systems. Nutrients move very slowly. Because they lack roots to absorb water and conducting tissues to transport it, they must absorb water directly from the air through their photosynthetic areas.

Cormophyte Nutrition

Cormophytes are higher plants that possess true tissues and organs, each performing specific functions. Roots, stems, and leaves are specialized for nutrition.

Water Uptake

Water is found in the soil, and the plant absorbs it through its roots via root hairs. Root hairs are outgrowths of epidermal cells, with each radical hair forming a unique cell. The surface of these hairs is covered by a mucilaginous layer, which allows for better adhesion to soil particles. This adhesion facilitates the uptake of water from the soil, which enters the root by osmosis.

Once inside the epidermal cells, water continues to move towards more internal zones of the root: through intercellular spaces and cell walls (apoplast pathway), as well as through the cells of the cortical parenchyma, endodermis, and pericycle (symplast pathway). When the water reaches the xylem conduits, it is transported to the stem and leaves.

Mineral Uptake

Minerals are also absorbed by the roots from the soil's ionic solution. Nutritional needs vary from species to species, but all plants require elements such as Ca, Mg, K, Na, P, Fe, and S.

Mineral uptake by the plant occurs via two distinct mechanisms:

• Apoplast Pathway: Mineral salts dissolved in water move through intercellular spaces and cellulose cell walls.
• Symplast Pathway: Only necessary ions enter, and a selection process occurs before reaching the endodermis. Ions selectively penetrate via active transport through the root hairs.

Additionally, some ions may be expelled from the roots back into the soil. This entire process is influenced by several factors, including temperature, pH, and soil moisture.