Dictionary:

pith

  (pĭth)

1. Botany. The soft, spongelike, central cylinder of the stems of most flowering plants, composed mainly of parenchyma.
2. Zoology. The soft inner substance of a feather or hair.
3. The essential or central part; the heart or essence. See synonyms at substance.
4. Strength; vigor; mettle.
5. Significance; importance.
6. Archaic. Spinal cord or bone marrow.

1. To remove the pith from (a plant stem).
2. To sever or destroy the spinal cord of, usually by inserting a needle into the vertebral canal.
3. To kill (cattle) by cutting the spinal cord.

[Middle English, from Old English pitha.]

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 also Parenchyma; Root (botany); Stem.

The soft, white, somewhat bitter, spongy layer that lies between the outer peel and the flesh of a citrus fruit.

noun

The most central and material part: core, essence, gist, heart, kernel, marrow, meat, nub, quintessence, root¹, soul, spirit, stuff, substance. Law gravamen. See be.

The soft central core of a log.

pith

1. destruction of the brain and spinal cord by thrusting a blunt needle into the vertebral canal and cranium, done on animals to destroy sensibility preparatory to experimenting on their living tissue.
2. an abattoir method of euthanasia; the animal is stunned by a captive bolt pistol and a cane or coiled wire passed into the cranium through the hole. The brain is destroyed by moving the cane about.

The soft spongelike tissue in the center of young stems and stalks.

For the helmet used in tropical and subtropical climates (and historic British Empire films, including Zulu), see Pith helmet.

The centre dark spot (about 1 mm diameter) in this yew wood is the pith

Elderberry shoot cut longitudinally to show the broad, solid pith (rough-textured, white) inside the wood (smooth, yellow-tinged). Scale in mm.

Walnut shoot cut longitudinally to show the chambered pith found in this genus. Scale in mm.

Pith is a light substance that is found in vascular plants. It consists of soft, spongy parenchyma cells, and is located in the center of the stem. It is encircled by a ring of xylem (woody tissue), and outside that, a ring of phloem (bark tissue). In most plants the pith is solid, but some plants, e.g. grasses and umbellifers, the pith has a hollow centre forming a hollow tube except at the points where leaves are produced, where there is a solid plate across the stem. A few plants, e.g. walnut, have distinctive chambered pith with numerous short cavities in the pith.

The word comes from the Old English word piþa, meaning substance, akin to Middle dutch pit, meaning the pit of a fruit.

The pith varies in diameter from about 0.5 mm to 6-8 mm in solid pith, and up to 150 mm or more in the stems of some plants with hollow pith, e.g. some bamboos. Freshly grown pith in young new shoots is typically white or pale brown, commonly darkening with age. In woody plants (trees, shrubs), the pith becomes surrounded by successive annual layers of wood; it may be very inconspicuous but is always present at the centre of a trunk or branch.

The cells in the peripheral parts of the pith may in some plants (e.g. Hedera helix) develop to be different from cells in the rest of the pith. This layer of cells is then called the perimedullary region of the pith.

The pith of the sola or other similar plants is used to make the pith helmet ^[1].

The pith of some plants, as sago, is edible to humans.

References

1. ^ AskOxford.com - Pith helmet

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Dansk (Danish)
n. - marv, kerne
v. tr. - tage marven ud af

Nederlands (Dutch)
zwaartepunt, essentie, (fysieke) kracht, het wit (van citrusvrucht), belang, ruggengraat, merg/wit verwijderen, ruggenmerg doorsnijden (slachten)

Français (French)
n. - peau blanche (d'un fruit), moelle, (fig) essence
v. tr. - retirer la m¯lle de, abattre (le bétail) en coupant la m¯lle épinière, détruire la m¯lle épinière (animal de laboratoire)

Deutsch (German)
n. - Mark, Kern
v. - das Mark entfernen

Ελληνική (Greek)
n. - (φυτολ.) εντεριώνη (κν. ψίχα, καρδιά), (μτφ.) ουσία, ουσιώδες μέρος, ζουμί, μεδούλι, ενεργητικότητα, σφρίγος, ρώμη, δύναμη, ενέργεια, σθένος
v. - αφαιρώ την ψίχα ή το μεδούλι

Italiano (Italian)
essenziale, nocciolo, estrarre il nocciolo

Português (Portuguese)
n. - medula (f), tutano (m), vigor (m)
v. - matar secionando a medula espinhal

Русский (Russian)
сердцевина, спинной мозг, суть, удалять сердцевину, перерезать спинной мозг

Español (Spanish)
n. - esencia, médula, meollo
v. tr. - matar cortando la médula, quitar la médula a

Svenska (Swedish)
n. - märg, ryggmärg, kärna, det viktigaste, det vita i apelsin, kraft, vigör
v. - slakta gnm att hugga av ryggmärgen

中文（简体） (Chinese (Simplified))
髓, 毛髓, 骨髓, 衬皮, 中果皮, 除去木髓, 杀死

中文（繁體） (Chinese (Traditional))
n. - 髓, 毛髓, 骨髓, 襯皮, 中果皮
v. tr. - 除去木髓, 殺死

한국어 (Korean)
n. - 속(식물에 있어서 줄기의 중심부를 이루는 부분), 핵심, 기운
v. tr. - 척수(고갱이)를 빼내다

日本語 (Japanese)
n. - 髄, 中果皮, 要点, 核心, 気力

العربيه (Arabic)
‏(الاسم) اللب, لب الثمرة, النسيج الاسفنجي المركز في ساق النبات, النقي : مخ العظم, لباب, الزبدة, الجوهر (فعل) يقتل الماشيه بقطع حبلها الشوكي, يعطل دماغ الضفدعه, ينزع اللب‏

עברית (Hebrew)
n. - ‮תמצית, עיקר, חוט השדרה, חומר ספוגי (בצמח), לשד, כוח, עוצמה, תוך, חשיבות‬
v. tr. - ‮הרג או שיתק (חיה), הוציא לשד של (חיה)‬

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