Laticifer

Laticifers are specialized secretory cells or ducts in plants that synthesize and transport latex, a milky or colored sap. They serve primarily a defensive function, producing a complex mixture that can deter herbivores and seal wounds. Laticifers may be non-articulated, consisting of a single elongated cell, or articulated, formed by a series of connected cells that extend through tissues. Articulated laticifers can form extensive networks, sometimes branching within various organs.

Laticifers occur in numerous plant families, including Apocynaceae, Euphorbiaceae, Moraceae, Papaveraceae, and others. They can be located in different tissues, such as the phloem region, cortex, or pith, and their distribution varies from species to species. The development of laticifers often involves differentiation from parenchyma or provascular tissues, with the resulting tubes or cells extending long distances within the plant.

The latex produced by laticifers is a colloidal suspension that typically contains water, sugars, proteins, alkaloids, terpenoids, lipids, and, in some species, rubber particles. In rubber-producing species like Hevea brasiliensis, latex contains natural rubber; in other species, latex lacks rubber but may carry alkaloids or other secondary metabolites. Upon injury, latex can exude and coagulate, forming a physical barrier and delivering chemical defenses to deter attack.

Ecological and economic significance varies by species. Latex-bearing plants have long been studied for plant defense mechanisms, and some laticiferous species are important sources of commercial products, including natural rubber and pharmaceutically active compounds.