Pith

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Elder shoot cut longitudinally to show the broad, solid pith (rough textured, white) inside the wood (smooth, yellow tinged). Scale in millimeters. Elder pith.jpg
Elder shoot cut longitudinally to show the broad, solid pith (rough textured, white) inside the wood (smooth, yellow tinged). Scale in millimeters.
Walnut shoot cut longitudinally to show the chambered pith found in this genus. Scale in millimeters. Walnut pith.jpg
Walnut shoot cut longitudinally to show the chambered pith found in this genus. Scale in millimeters.

Pith, or medulla, is a tissue in the stems of vascular plants. 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.

Contents

While new pith growth is usually white or pale in color, as the tissue ages it commonly darkens to a deeper brown color. In trees pith is generally present in young growth, but in the trunk and older branches the pith often gets replaced – in great part – by xylem. In some plants, the pith in the middle of the stem may dry out and disintegrate, resulting in a hollow stem. A few plants, such as walnuts, have distinctive chambered pith with numerous short cavities (see image at middle right). The cells in the peripheral parts of the pith may, in some plants, develop to be different from cells in the rest of the pith. This layer of cells is then called the perimedullary region of the pithamus. An example of this can be observed in Hedera helix, a species of ivy.

The term pith is also used to refer to the pale, spongy inner layer of the rind, more properly called mesocarp or albedo, of citrus fruits (such as oranges) and other hesperidia. The word comes from the Old English word piþa, meaning substance, akin to Middle Dutch pitte (modern Dutch pit), meaning the pit of a fruit. [2]

Uses

Food

The pith of the sago palm, although highly toxic to animals in its raw form, is an important human food source in Melanesia and Micronesia by virtue of its starch content and its availability. There is a simple process of starch extraction from sago pith that leaches away a sufficient amount of the toxins and thus only the starch component is consumed. Current processes for starch extraction are generally only about 50% efficient, however, with the other half remaining in residual pith waste. [3] The form of the starch after processing is similar to tapioca.

Other foods sometimes mistakenly called piths include heart of palm (actually the core of the bud) and banana piths (actually the rolled up young leaves).

The tiny central dark spot (diameter: about 1-millimeter (0.039 in)) in this yew wood is the pith Taxus wood.jpg
The tiny central dark spot (diameter: about 1-millimeter (0.039 in)) in this yew wood is the pith

Pith helmets

The spongy wood of the pith wood plant or other similar species, often mistakenly called pith, was once used to make pith helmets. [4] [5]

Watch cleaning

Pith wood is a cleaning tool used in watchmaking to clean watch parts [6] :144 and tools. It is used to remove oil from the tips of tools to prevent the contamination of watch movements. A pith wood consists of a piece of pith (such as elder [6] :281 or mullein [7] ).

Light

Dried pith (which is actually the center of the leaf) of certain rush plants soaked in fat or grease, held using a rushlight, was used as home lighting. Beginning in the 17th century, it would continue to be used in this method until the mid-20th century. It saw a brief revival during World War 2.

Related Research Articles

<span class="mw-page-title-main">Plant cell</span> Type of eukaryotic cell present in green plants

Plant cells are the cells present in green plants, photosynthetic eukaryotes of the kingdom Plantae. Their distinctive features include primary cell walls containing cellulose, hemicelluloses and pectin, the presence of plastids with the capability to perform photosynthesis and store starch, a large vacuole that regulates turgor pressure, the absence of flagella or centrioles, except in the gametes, and a unique method of cell division involving the formation of a cell plate or phragmoplast that separates the new daughter cells.

Palm most commonly refers to:

<span class="mw-page-title-main">Sago</span> Starch extracted from tropical palm stems

Sago is a starch extracted from the pith, or spongy core tissue, of various tropical palm stems, especially those of Metroxylon sagu. It is a major staple food for the lowland peoples of New Guinea and the Maluku Islands, where it is called saksak, rabia and sagu. The largest supply of sago comes from Southeast Asia, particularly Indonesia and Malaysia. Large quantities of sago are sent to Europe and North America for cooking purposes. It is traditionally cooked and eaten in various forms, such as rolled into balls, mixed with boiling water to form a glue-like paste (papeda), or as a pancake.

<span class="mw-page-title-main">Tissue (biology)</span> Group of cells having similar appearance and performing the same function

In biology, tissue is a historically derived biological organizational level between cells and a complete organ. A tissue is therefore often thought of as an assembly of similar cells and their extracellular matrix from the same embryonic origin that together carry out a specific function. Organs are then formed by the functional grouping together of multiple tissues.

<span class="mw-page-title-main">Bark (botany)</span> Outermost layers of stems and roots of woody plants

Bark is the outermost layer of stems and roots of woody plants. Plants with bark include trees, woody vines, and shrubs. Bark refers to all the tissues outside the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner bark, which in older stems is living tissue, includes the innermost layer of the periderm. The outer bark on older stems includes the dead tissue on the surface of the stems, along with parts of the outermost periderm and all the tissues on the outer side of the periderm. The outer bark on trees which lies external to the living periderm is also called the rhytidome.

<span class="mw-page-title-main">Vascular cambium</span> Main growth tissue in the stems, roots of plants

The vascular cambium is the main growth tissue in the stems and roots of many plants, specifically in dicots such as buttercups and oak trees, gymnosperms such as pine trees, as well as in certain other vascular plants. It produces secondary xylem inwards, towards the pith, and secondary phloem outwards, towards the bark.

"Rice paper" has many varieties such as rice paper made from tree bark to make drawing and writing paper or from rice flour and tapioca flour and then mixed with salt and water to produce a thin rice cake and dried to become harder and paper-like. It is used to wrap many ingredients when eating. Vietnam is the only country that creates edible rice paper from the process of making rice noodles and pho noodles. Rice paper is a product constructed of paper-like materials made from different plants. These include:

<span class="mw-page-title-main">Trunk (botany)</span> Main wooden axis of a tree

In botany, the trunk is the stem and main wooden axis of a tree, which is an important feature in tree identification, and which often differs markedly from the bottom of the trunk to the top, depending on the species. The trunk is the most important part of the tree for timber production.

In a vascular plant, the stele is the central part of the root or stem 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. Outside the stele lies the endodermis, which is the innermost cell layer of the cortex.

<i>Calamites</i> Extinct genus of vascular plants in the Order Equisetales

Calamites is a genus of extinct arborescent (tree-like) horsetails to which the modern horsetails are closely related. Unlike their herbaceous modern cousins, these plants were medium-sized trees, growing to heights of 30-50 meters. They were components of the understories of coal swamps of the Carboniferous Period.

<i>Cycas revoluta</i> Species of plant

Cycas revoluta is a species of gymnosperm in the family Cycadaceae, native to southern Japan including the Ryukyu Islands. It is one of several species used for the production of sago, as well as an ornamental plant. The sago cycad can be distinguished by a thick coat of fibers on its trunk. The sago cycad is sometimes mistakenly thought to be a palm, although the only similarity between the two is that they look similar and both produce seeds.

<span class="mw-page-title-main">Cortex (botany)</span> Outer layer of a stem or root in a vascular plant

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. The cortex is composed mostly of large thin-walled parenchyma cells of the ground tissue system and shows little to no structural differentiation. The outer cortical cells often acquire irregularly thickened cell walls, and are called collenchyma cells.

<span class="mw-page-title-main">Ground tissue</span> Various non-vascular tissues in plants

The ground tissue of plants includes all tissues that are neither dermal nor vascular. It can be divided into three types based on the nature of the cell walls. This tissue system is present between the dermal tissue and forms the main bulk of the plant body.

  1. Parenchyma cells have thin primary walls and usually remain alive after they become mature. 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.
  2. 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.
  3. Sclerenchyma cells have thick lignified secondary walls and often die when mature. Sclerenchyma provides the main structural support to a plant.
<span class="mw-page-title-main">Vascular tissue</span> Conducting tissue in vascular plants

Vascular tissue is a complex conducting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem. These two tissues transport fluid and nutrients internally. There are also two meristems associated with vascular tissue: the vascular cambium and the cork cambium. All the vascular tissues within a particular plant together constitute the vascular tissue system of that plant.

<span class="mw-page-title-main">Secondary growth</span> Type of growth in plants

In botany, secondary growth is the growth that results from cell division in the cambia or lateral meristems and that causes the stems and roots to thicken, while primary growth is growth that occurs as a result of cell division at the tips of stems and roots, causing them to elongate, and gives rise to primary tissue. Secondary growth occurs in most seed plants, but monocots usually lack secondary growth. If they do have secondary growth, it differs from the typical pattern of other seed plants.

<i>Metroxylon sagu</i> Species of palm

Metroxylon sagu, the true sago palm, is a species of palm in the genus Metroxylon, native to tropical southeastern Asia. The tree is a major source of sago starch.

<span class="mw-page-title-main">Woody plant</span> Plant that produces wood and has a hard stem

A woody plant is a plant that produces wood as its structural tissue and thus has a hard stem. In cold climates, woody plants further survive winter or dry season above ground, as opposed to herbaceous plants that die back to the ground until spring.

<span class="mw-page-title-main">Plant stem</span> Structural axis of a vascular plant

A stem is one of two main structural axes of a vascular plant, the other being the root. It supports leaves, flowers and fruits, transports water and dissolved substances between the roots and the shoots in the xylem and phloem, photosynthesis takes place here, stores nutrients, and produces new living tissue. The stem can also be called halm or haulm or culms.

<span class="mw-page-title-main">Leaf</span> Photosynthetic part of a vascular plant

A leaf is a principal appendage of the stem of a vascular plant, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, flower, and fruit collectively form the shoot system. In most leaves, the primary photosynthetic tissue is the palisade mesophyll and is located on the upper side of the blade or lamina of the leaf but in some species, including the mature foliage of Eucalyptus, palisade mesophyll is present on both sides and the leaves are said to be isobilateral. Most leaves are flattened and have distinct upper (adaxial) and lower (abaxial) surfaces that differ in color, hairiness, the number of stomata, the amount and structure of epicuticular wax and other features. Leaves are mostly green in color due to the presence of a compound called chlorophyll which is essential for photosynthesis as it absorbs light energy from the sun. A leaf with lighter-colored or white patches or edges is called a variegated leaf.

Sholapith or shola pith is a dried milky-white spongey plant matter from Aeschynomene species. It can be pressed and shaped into objects of art, or for practical use. It is the "pith" used for pith helmets, so giving them their name.

References

  1. Urry, Lisa A.; Cain, Michael Lee; Wasserman, Steven Alexander; Minorsky, Peter V.; Orr, Rebecca B. (November 11, 2023). Campbell Biology. Pearson. p. 770. ISBN   978-0-135-18874-3.
  2. "Pith". Dictionary.com Unabridged. Random House, Inc. Retrieved January 20, 2011.
  3. Mishima, Takashi (2018). "New Sago Palm Starch Resources and Starch Pith Waste Properties". In Ehara, H.; Toyoda, Y.; Johnson, D. (eds.). Sago Palm. Singapore: Springer. pp. 309–315. doi:10.1007/978-981-10-5269-9_23. ISBN   978-981-10-5268-2.
  4. AskOxford.com - Pith helmet
  5. Batello, Caterina; Marzot, Marzio; Touré, Adamou Harouna (2004). "5. Farming Systems" (PDF). The Future is an Ancient Lake. Rome: Food and Agriculture Organization Interdepartmental Working Group on Biological Diversity for Food and Agriculture. p. 154. ISBN   92-5-105064-3.
  6. 1 2 Britten, Frederick James (1896), The Watch & Clock Makers' Handbook, Dictionary and Guide, Spon, p. 144
  7. Stelle, J. Parish (2017), The American Watchmaker and Jeweler: A Full and Comprehensive Exposition of all the Latest and most Approved Secrets of the Trade Embracing Watch and Clock Cleaning and Repairing, Tempering in all its Grades, Making Tools, Compounding Metals, Soldering, Plating, Etc., Read Books, ISBN   9781473339408