Meristems are localized regions of cell division that are the sources of all new organs in the adult plant. Apical meristems are responsible for primary growth, which is associated with the lengthening and branching of shoots and roots. Lateral meristems increase plant thickness and form wood and bark in many eudicots.
learning outcomes
You should be able to:
Describe characteristics of determinate and indeterminate growth in plants.
Compare meristematic with non-
Analyze how apical meristems are able to produce different organs, including leaves, stems, flowers, and roots.
Describe or illustrate a longitudinal section of the developing root, and explain the functions of special zones of cells from the tip upward.
Explain how different types of meristem result in the various layers of the mature root.
How can an apical meristem be maintained for years while continuing to form leaves?
An apical meristem has stem cells that continuously divide. Some of the daughter cells form new organs (e.g., leaves), but others remain to divide further as part of the undifferentiated pool.
Define the primary meristems of the plant and how tissues and organs are formed from them.
Root and shoot apical meristems give rise to primary meristems, which are responsible for primary growth of plants and form all plant tissues. There are three primary meristems: (1) protoderm forms dermal tissues; (2) ground meristem forms ground tissues; and (3) procambium forms vascular tissues.
What cells are derived from the root apical meristem, and what is the general process of root growth?
The root apical meristem forms the root cap and root primary meristem. The latter forms the dermal, ground, and vascular tissues of the root. The root grows by cell expansion in a region just above the root apical meristem.
Compare primary and secondary growth in a tree trunk in terms of the meristems involved, the tissues formed, and the result.
Primary: apical meristem; secondary: lateral meristem (vascular cambium) and lateral meristem (cork cambium)
Primary: Xylem, phloem, parenchyma, dermal tissue
Secondary: Secondary xylem and phloem; cork
Primary: growth in length
Secondary: Growth in thickness
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The building of the plant body by meristems allows a plant to respond to its environment by redirecting its growth. Thus individual plants of the same species can vary greatly in form. What underlies this variation, and how have we humans used it to our advantage?