What are meristems and why are they important?

Question

What are meristems and why are they important?

Answer 1

growth and differentiation

Answer 2

A meristem is a tissue in all plants consisting of undifferentiated cells (meristematic cells) and found in zones of the plant where growth can take place.

The term “meristem” was first used by Karl Wilhelm von Nägeli (1817-1891) from his book “Beiträge zur Wissenschaftlichen Botanik” in 1858. It is derived from the Greek word “merizein”, meaning to divide in recognition of its inherent function.

Differentiated plant cells generally cannot divide or produce cells of a different type. Therefore, cell division in the meristem is required to provide new cells for expansion and differentiation of tissues and initiation of new organs, providing the basic structure of the plant body.

Meristematic cells are analogous in function to stem cells in animals, are incompletely or not at all differentiated, and are capable of continued cellular division (youthful). Furthermore, the cells are small and protoplasm fills the cell completely. The vacuoles are extremely small. The cytoplasm does not contain differentiated plastids (chloroplasts or chromoplasts), although they are present in rudimentary form (proplastids). Meristematic cells are packed closely together without intercellular cavities. The cell wall is a very thin primary cell wall.

Answer 3

A meristem is a tissue in all plants consisting of undifferentiated cells (meristematic cells) and found in zones of the plant where growth can take place.

(((Importance of Meristems - In plants , growth is impossibe with out meristem)))

The term “meristem” was first used by Karl Wilhelm von Nägeli (1817-1891) from his book “Beiträge zur Wissenschaftlichen Botanik” in 1858. It is derived from the Greek word “merizein”, meaning to divide in recognition of its inherent function.

Details with illustrations on the links below . Click on them --

http://en.wikipedia.org/wiki/Meristem

http://www.sbs.utexas.edu/mauseth/weblab...

http://www.answers.com/topic/meristem

http://www.answers.com/topic/cambium

http://images.google.co.in/images?hl=en&...

Answer 4

A meristem or bud is a rapidly dividing area of plant tissue from which new plant parts arise.

Apical meristems are the completely undifferentiated (indeterminate) meristems in a plant. These differentiate into three kinds of primary meristems. The primary meristems in turn produce the two secondary meristem types. These secondary meristems are also known as lateral meristems because they are involved in lateral growth.

At the meristem summit there is a small group of slowly dividing cells which is commonly called the central zone. Cells of this zone have a stem cell function and are essential for meristem maintenance. The proliferation and growth rates at the meristem summit usually differ considerably from those at the periphery.

The apical meristem, or growing tip, is a completely undifferentiated meristematic tissue found in the buds and growing tips of roots in plants. Its main function is to begin growth of new cells in young seedlings at the tips of roots and shoots (forming buds, among other things). Specifically, an active apical meristem lays down a growing root or shoot behind itself, pushing itself forward. Apical meristems are very small, compared to the cylinder-shaped lateral meristems .

Apical meristems are composed of several layers. The number of layers varies according to plant type. In general the outermost layer is called the tunica while the innermost layers are the corpus. In monocots, the tunica determine the physical characteristics of the leaf edge and margin. In dicots, layer two of the corpus determine the characteristics of the edge of the leaf. The corpus and tunica play a critical part of the plant physical appearance as all plant cells are formed from the meristems. Apical meristems are found in two locations: the root and the stem. Some arctic plants have a apical meristem in the lower/middle parts of the plant. It is thought that this kind of meristem evolved because it is advantageous in arctic conditions.

Answer 5

The meristem,are a group of multipotent cells that can generate organs, has regenerative properties, and is self-organizing.There are two types of meristem in plants, the above ground portion in the shoot and the below ground portion of the root .The shoot apical meristem produces leaves, buds, and stem. The root apical meristem produces the root and responds to gravitational cues. The shoot apical meristem is organized into zones and layersThere are two zones, a central zone located in the center of the meristem, surrounded by a peripheral zone.The meristem continually produces new leaves, which are visible as they initiate as slight bumps, or primordia, at the periphery of the meristem.

Not only are leaves initiated from meristems during plant development, but also new branches are initiated from axillary meristems located at leaf axil junctions along the main stem. The growth of axillary meristems is normally suppressed by the shoot apical meristem. However, if the shoot apical meristem is removed, by pruning for example, then the axillary meristems will grow into new flowering shoots and branches . This phenomenon by which the growth of apical meristems is suppressed by the shoot apical meristem is called apical dominance. Apical dominance also suppresses the growth of adventitious meristems, which form along the surface of stems and leaves. Hormonal signals are important for the mechanism of apical dominance and affect the growth of both axial and adventitious meristems.

Another important meristem is the root apical meristem ,which is organized into four zones at the tip of the root: a root cap, a zone of cell division, a zone of elongation, and a zone of differentiation.



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