pericycle

[per-uh-sahy-kuhl]

noun

Botany.

1. the outermost cell layer of the stele in a plant, frequently becoming a multilayered zone.

pericycle

/ -ˈsɪk-, ˌpɛrɪˈsaɪklɪk, ˈpɛrɪˌsaɪkəl /

noun

1. a layer of plant tissue beneath the endodermis: surrounds the conducting tissue in roots and certain stems

pericycle

1. A layer of nonvascular tissue that surrounds the vascular tissues in the roots of plants and is in turn surrounded by the endodermis. New lateral roots begin growth from the pericycle.

Other Word Forms

• pericyclic adjective

Word History and Origins

Origin of pericycle¹

From the Greek word períkyklos, dating back to 1890–95. See peri-, cycle

Word History and Origins

Origin of pericycle¹

C19: from Greek perikuklos

Example Sentences

The irritated pericycle and cortex then grow and form nodules of soft juicy root-tissue at which the insect continues to suck.

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After the cambium has been active for some time producing secondary xylem and phloem, the latter consisting of sieve-tubes, phloem-parenchyma and frequently thick-walled fibres, a second cambium is developed in the pericycle; this produces a second vascular zone, which is in turn followed by a third cambium, and so on, until several hollow cylinders are developed.

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The endodermis in Pinus, Picea and many other genera is usually a well-defined layer of cells enclosing the vascular bundles, and separated from them by a tissue consisting in part of ordinary parenchyma and to some extent of isodiametric tracheids; but this tissue, usually spoken of as the pericycle, is in direct continuity with other stem-tissues as well as the pericycle.

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It has been suggested that transfusion-tracheids represent, in part at least, the centripetal xylem, which forms a distinctive feature of cycadean leaf-bundles; these short tracheids form conspicuous groups laterally attached to the veins in Cunninghamia, abundantly represented in a similar position in the leaves of Sequoia, and scattered through the so-called pericycle in Pinus, Picea, &c.

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The root is diarch in structure, but additional protoxylem-strands may be present at the base of the main root; the pericycle consists of several layers of cells.

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