Classification of Meristem

Meristem is not a single uniform thing - the same actively-dividing tissue is classified four separate ways depending on what question you are asking about it. Ask where it sits in the plant body and you get apical meristem (at root and shoot tips, driving growth in length), intercalary meristem (a leftover band between already-mature tissues, stretching an internode), and lateral meristem (a cylinder running the length of the axis, thickening it - the vascular cambium and cork cambium). Ask when in development it arose and you get primary meristem (straight from the embryo, building the plant's first permanent tissues) versus secondary meristem (appearing later, producing cork cambium and interfascicular cambium for secondary growth). Ask what it becomes and you get protoderm (destined for the epidermal tissue system), procambium (destined for primary xylem and phloem) and ground meristem (destined for everything else - cortex and pith). Ask how its cells divide and you get mass meristem (dividing in every plane at once, as in a young embryo or endosperm), rib/file meristem (dividing anticlinally in one plane, building cortex and pith) and plate mer …