Shoot apical meristemThe dome of dividing cells at the tip. New leaves and stem tissue start here.
Leaf primordiumA small bump beside the dome. It grows into a leaf.
Young leafA leaf that has grown on from a primordium. The youngest leaves are nearest the tip.
Axillary bud primordiumA small mound in the leaf axil. It can grow into a branch.
ProtodermThe outer layer of cells. It becomes the epidermis.
Ground meristemThe tissue around and between the strands. It becomes the cortex and the pith.
ProcambiumNarrow strands that run into the leaves. They become the xylem and the phloem.
Root tip 4
Root capA thimble of cells over the tip. It shields the meristem behind it.
Root apical meristemThe region of dividing cells behind the root cap. It adds cells to the root and to the cap.
Quiescent centerA small group of cells in the root apical meristem. It keeps the cells around it as stem cells.
Zone of elongationThe stretch where the new cells grow longer. It pushes the tip forward.
How this list was compiled: Every name and statement was checked on 2026-10-03 against sources read that day; a name is kept only when two of them use it. (1) Wikipedia, text only: Meristem, https://en.wikipedia.org/wiki/Meristem (apical meristems give rise to primary growth and to three primary meristems: the protoderm, around the outside, which develops into the epidermis; the procambium, which develops into primary xylem and primary phloem; the ground meristem, which develops into the cortex and the pith; every above-ground organ comes from a shoot apical meristem, with leaf primordia on the flanks; the root apical meristem is covered at its apex by the root cap and holds an organizing center, the quiescent center, which maintains the surrounding stem cells), Primordium, https://en.wikipedia.org/wiki/Primordium (leaf primordia are groups of cells near the top of the shoot that form new leaves), Axillary bud, https://en.wikipedia.org/wiki/Axillary_bud (a bud in the axil of a leaf, with the potential to form a shoot), Root cap, https://en.wikipedia.org/wiki/Root_cap (it covers the very tip of the root and shields the apical meristem), and Root, https://en.wikipedia.org/wiki/Root (root cap, apical meristem, elongation zone; elongation pushes the root tip forward). (2) Adriance S. Foster, Practical Plant Anatomy, second edition, 1949, a university laboratory manual, read on archive.org, https://archive.org/details/in.ernet.dli.2015.240893 (the shoot apex as the region where leaves, buds and the primary meristematic tissues begin; the three primary meristems after Haberlandt: protoderm, from which the epidermis is derived, procambium, from which the primary vascular system develops, and ground meristem, from which the cortex and the pith arise; a procambial strand grows up into each leaf primordium; the drawing exercise lists leaf primordium, axillary bud primordium and procambial strand; the root apex differs from the shoot apex in its root cap, a thimble-shaped structure that buffers the meristem behind it). (3) John N. Martin, Botany for Agricultural Students, 1919, public domain, https://archive.org/details/botanyforagricul00mart (pages 126, 127, 144, 145 and 183: meristems at the stem and root tips, by which roots and stems elongate; the apical meristems are primary meristems; leaves are younger and more crowded the nearer the tip; the root tip in lengthwise section: the root cap, the zone of dividing cells next to it, which adds cells both to the cap and to the growth zone, and the zone of elongation). (4) The summaries of two journal papers, read in Europe PMC: Planta 2000, PMID 10923700 (the quiescent center, found in the root tip meristem of every angiosperm and gymnosperm, keeps the initial cells round it as stem cells), and Physiologia Plantarum 2016, PMID 26968317 (the root apical meristem; the quiescent center maintains the surrounding stem cells). Licence: own work
The drawing: Drawn for this site on 2026-10-03 from plain geometry; own work, nothing traced. Licence: own work
How it works
An apical meristem labeled at both ends of the plant: the dome at the tip of the shoot, with the leaf primordia it makes, and the meristem at the tip of the root, behind its root cap.
Read the full guide
The shoot tip
The shoot apical meristem is a small dome of dividing cells. Leaf primordia rise on its sides and grow into young leaves, and a bud primordium forms in each leaf axil. Below the dome lie three primary meristems: protoderm, procambium and ground meristem.
The root tip
The root apical meristem sits just behind the root cap, which it also renews. In it lies the quiescent center. Above the meristem, in the zone of elongation, the new cells grow longer.
Protoderm becomes the epidermis, procambium the xylem and phloem, and ground meristem the cortex and the pith.
A root tip has a cap and no leaf primordia. A shoot tip has leaf primordia and no cap.
Questions and answers
What is an apical meristem?
A group of dividing cells at the tip of a shoot or a root. Its new cells make the stem and the root grow longer, which is called primary growth.
Where are apical meristems found?
At the tip of every shoot and every root. On the shoot the meristem sits among the youngest leaves; on the root it lies just behind the root cap.
What are the three primary meristems?
Protoderm, procambium and ground meristem. Protoderm becomes the epidermis, procambium becomes the primary xylem and phloem, and ground meristem becomes the cortex and the pith.
What is the quiescent center?
A small group of cells in the root apical meristem. It keeps the cells that surround it as stem cells.
How does a shoot apical meristem differ from a root apical meristem?
The shoot apical meristem is at the very tip and makes leaf and bud primordia on its sides. The root apical meristem makes no leaves, lies behind a root cap, and adds cells to the cap as well as to the root.