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Parenchyma forms the "filler" tissue in the soft parts of plants, and is usually present in cortex, pericycle, pith, and medullary rays in primary stem and root. Collenchyma cells have thin primary walls with some areas of secondary thickening. Collenchyma provides extra mechanical and structural support, particularly in regions of new growth.
Pith is composed of soft, spongy parenchyma cells, which in some cases can store starch. In eudicotyledons, pith is located in the center of the stem. In monocotyledons, it extends only into roots. [1] The pith is encircled by a ring of xylem; the xylem, in turn, is encircled by a ring of phloem.
Cross-section of a flax plant stem: 1. Pith 2. Protoxylem 3. Xylem I 4. Phloem I 5. Sclerenchyma 6. Cortex 7. Epidermis. In botany, a cortex is an outer layer of a stem or root in a vascular plant, lying below the epidermis but outside of the vascular bundles. [1]
In a vascular plant, the stele is the central part of the root or stem [1] containing the tissues derived from the procambium. These include vascular tissue , in some cases ground tissue ( pith ) and a pericycle , which, if present, defines the outermost boundary of the stele.
ABA is an applied science devoted to developing procedures which will produce observable changes in behavior. [3] [9] It is to be distinguished from the experimental analysis of behavior, which focuses on basic experimental research, [10] but it uses principles developed by such research, in particular operant conditioning and classical conditioning.
The stem can also be called the culm, halm, haulm, stalk, or thyrsus. The stem is normally divided into nodes and internodes: [2] The nodes are the points of attachment for leaves and can hold one or more leaves. There are sometimes axillary buds between the stem and leaf which can grow into branches (with leaves, conifer cones, or flowers). [2]
Psychological assessment is similar to psychological testing but usually involves a more comprehensive assessment of the individual. According to the American Psychological Association, psychological assessment involves the collection and integration of data for the purpose of evaluating an individual’s "behavior, abilities, and other ...
Pith – the spongy tissue at the center of a stem. Chambered pith – a form of pith in which the parenchyma collapses or is torn during development, leaving the sclerenchyma plates to alternate with hollow zones; Diaphragmed pith – pith in which plates or nests of sclerenchyma may be interspersed with the parenchyma.