procambial

Procambial refers to the procambium, a primary meristem in plants that gives rise to the vascular tissues of the organism. The procambium originates during primary growth from provascular tissue produced by the apical meristem and lies between the protoderm (future epidermis) and the ground meristem (future cortex and pith). Its cells divide and differentiate to form primary xylem and primary phloem, organized as vascular bundles in stems and leaves or as the vascular cylinder in roots.

In stems, the early procambium typically differentiates into discrete vascular bundles arranged in patterns that vary among species, with xylem typically interior and phloem exterior. In roots, procambial tissue differentiates into a central stele containing xylem and phloem, often organized as a solid core in cross-section. In leaves, procambial strands extend from the stem into developing leaf primordia, forming the leaf’s vascular network. As leaves mature, these strands differentiate into vascular bundles with xylem on the interior and phloem toward the outer side, and in some taxa, interfascicular cambium can form for lateral growth.

Historically, procambial tissue is distinguished from protoderm (epidermis) and ground meristem (cortex, pith, or mesophyll) by its role in forming vascular tissue. The term procambial is used to describe cells, tissues, or developmental stages associated with this meristem.