pith


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pith,

in botany, core of the stemstem,
supporting structure of a plant, serving also to conduct and to store food materials. The stems of herbaceous and of woody plants differ: those of herbaceous plants are usually green and pliant and are covered by a thin epidermis instead of by the bark of woody plants.
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 of most plants. Pith is composed of large, loosely packed food-storage cells. As the stem grows older the pith usually dries out, and in some it disintegrates and the stem becomes hollow. In trees the pith becomes much reduced as the woody tissue (xylem) grows. In East Asia, rice paper is made from the pith of some shrubs. Candlewicks are made of the pith of certain rushes.

Pith

The central zone of tissue of an axis in which the vascular tissue is arranged as a hollow cylinder. Pith is present in most stems and in some roots. Stems without pith rarely occur in angiosperms but are characteristic of psilopsids, lycopsids, Sphenophyllum, and some ferns. Roots of some ferns, many monocotyledons, and some dicotyledons include a pith, although most roots have xylem tissue in the center.

Pith is composed usually of parenchyma cells often arranged in longitudinal files. This arrangement results from predominantly transverse division of pith mother cells near the apical meristem. See Parenchyma, Root (botany), Stem

Pith

 

the central portion of a plant stem, consisting of loose parenchymatous tissue. The internal part of the pith sometimes ruptures with age, forming one large air cavity (Labiatae, Um-belliferae, some Gramineae) or several cavities (grape). Roots have no typical pith. Pith usually consists mainly of thin-walled cells, among which there may be lignified thick-walled cells (apple), latex vessels (Campanulaceae, Convulvulaceae), mucous cells (linden), or canals with volatile oils (Compositae, Umbel-liferae). The parenchymatous cells contain reserve starch, which in woody plants is concentrated mainly in external small-celled layers of the pith—the perimedullary zone. Druses or single crystals of calcium oxalate are often found in the pith.

pith

[pith]
(botany)
A central zone of parenchymatous tissue that occurs in most vascular plants and is surrounded by vascular tissue.

pith

pith
The soft central core of a log.

pith

1. the soft fibrous tissue lining the inside of the rind in fruits such as the orange and grapefruit
2. Botany the central core of unspecialized cells surrounded by conducting tissue in stems
3. the soft central part of a bone, feather, etc.
References in periodicals archive ?
The pith location did not necessarily have an influence on the volumetric shrinkage.
The regression analysis showed that shrinkage declined significantly with increasing age (number of growth rings from the pith) and that the relationship between shrinkage and age changed significantly at age 15, with shrinkage leveling off after that age.
The first pattern showed an initial positive GAdisc value that decreased as the distance from the pith increased (Fig.
For example, Bendtsen and Senft (1986) reported that the xylem after the 13th ring from the pith was determined to be mature wood by using the radial variations in the MOE, MOR, compressive strength, and ovendry density.
92.46%, significantly lower than that of other fractions, i.e., 93.05% to 93.78% in tassel and leaf sheath; 95.16% to 95.58% in whole plant, stem pith, and stem node; and 96.92% to 97.27% in ear husk and stem rind.
Much amount of sugarcane pith is produced annually in the world including Iran.
Logs were graded to the damage type that most lowered the internal quality (e.g., log with soft rot may also contain hard rot, hard rot in pith, or color defect in pith).
The backcrossed seed from the solider and more fertile plants were increased in a growth cabinet and scored for pith development.
A Channel 5 spokesman said: "We're sorry that Keith won't do it again, but if we have another programme we'll be open to suggestions as to who can fill Keith's pith helmet."
It rights the defects of Donald Miller's chatterbox biography of 1989 by drawing out from Mumford's oeuvre the pith of his thought about building, planning and society.
And by reversing the direction of juice flow through the column, the researchers have overcome clogging by pith and other solids that cloud unfiltered juice.