Metabolites are substances that help in metabolism. Some substances help in metabolism, but when they are produced in excess amounts, they remain outside the cell. Many algae produce extracellular metabolites such as lipids, glycolates, proteins, amino acids, vitamins, phenolic compounds, and organic acids.    

The secondary xylem which is formed after secondary growth of woody dicotyledons is called wood. However, all secondary xylem is not wood, e.g., secondary xylem formed after secondary growth in herbaceous dicots. On the other hand, in the Conifers group of Gymnosperm, the secondary xylem developed after secondary growth is …