Pericycle


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Related to Pericycle: xylem, Medullary rays

pericycle

[′per·ə‚sī·kəl]
(botany)
The outer boundary of the stele of plants; may not be present as a distinct layer of cells.

Pericycle

 

(also pericambium), formative tissue in the roots and the stems of plants, located around the vascular cylinder. The pericycle is represented by one or more (in gymnosperms) layers of parenchymatous cells of the meristem, which are separated from the cells of the primary cortex by the endodermis. All lateral roots develop from the pericycle of the main root. In dicotyledonous plants, action of the pericyclic cells causes the cambial cells to join in a common cylinder in the roots of secondary growth. The pericycle forms broad rays in the root, in whose parenchyma metabolic products are deposited and new adventitious roots and, sometimes, root buds are formed. When the root thickens and the primary cortex atrophies, the phellogen is differentiated in the pericycle, forming the periderm on the surface of the root.

Pericycle in the stems of plants gives rise to both sclerenchyma and parenchyma (some lianas of the families Aristolochiaceae, Cucurbitaceae, and Solanaceae) or to only sclerenchyma (in monocotyledons). In many species of Compositae (viper’s grass, dandelion), segmented latex vessels are formed in the pericycle. In Umbelliferae, essential-oil passages are formed, and in Cucurbitaceae secretory cells. In some plants of the families Liliaceae, Chenopodiaceae, and Caryophyllaceae, secondary thickening of stems and roots occurs owing to the formation from the pericycle of new layers of cambial zones and vascular bundles to the periphery of the vascular cylinder. The thickening is associated with the formative function of pericyclic cells. This type of secondary thickening of axial organs of a plant is usually called anomalous growth.

I. S. MIKHAILOVSKAIA

References in periodicals archive ?
In the central cylinder of all of the species, the uniseriate pericycle with cells with fine walls, come with variations in the size and cellular form, in Polygonum ferrugineum (Figure 3D), P.
Directly outside the pericycle is a single layer of cells called the endodermis.
Silva (2006) reported that plants contaminated with heavy metals have a decrease in the thickness of the pericycle, a variation that is attributed to probable alterations in photosynthetic rates.
The central cylinder is composed of parenchymatous uniseriate pericycle and alternate bundles of primary xylem and phloem (Figure 2D).
ARL1 is an auxin-responsive factor involved in auxin-mediated cell dedifferentiation, and that it promotes the initial cell division in the pericycle cells adjacent to the peripheral vascular cylinder in the stem (Liu et al.
As it moves from the epidermal cells to the xylem, water passes through the root cortex, endodermis, and pericycle.
Once past the endodermis, water moves through the pericycle, a layer of cells from which the new lateral roots originate.
The transmission of pathogen from roots to fruit might be the outcome of passive routing from wounds in the pericycle, mesophyl, and periderm of secondary lateral roots or natural openings resulting through damage during transplanting or growth (Hallman et al.
According to them, in some species, such as Zingiber officinale (Zingiberaceae), the observation of Casparian bands in the endodermis allowed researchers to verify that the pericycle is involved in the tuberisation process of the rhizome.
Secondary growth is similar to verified type for most of the dicots roots, cambium with procambium, and phellogen that also origins from pericycle.
As previously reported, the shading condition maintained the auxin level in the shoots, stimulating the pericycle to form adventitious roots at the shoot nodes.
19-22) developed from cell divisions of pericycle and phloem parenchyma (Fig.