What are the three most common types of collenchyma?

The three most common types of collenchyma, classified based on the pattern of cell wall thickening, are: (1) Angular collenchyma, where thickening occurs at the corners where cells meet, commonly found in stems of many herbaceous plants; (2) Lamellar (plate) collenchyma, characterized by thickening on tangential walls (walls parallel to the surface), often seen in stems of some dicots; and (3) Lacunar collenchyma, which has thickening around intercellular spaces, providing flexibility while maintaining support. These living cells with unevenly thickened primary walls provide flexible mechanical support to growing plant organs, allowing them to bend without breaking while supporting young stems, petioles, and leaf veins.