Pith

Pith, or medulla, is a tissue in the stems of vascular plants. Pith is composed of soft, spongy parenchyma cells, which store and transport nutrients throughout the plant. In eudicots, pith is located in the center of the stem. In monocots, it extends also into flowering stems and roots. The pith is encircled by a ring of xylem; outside followed by a ring of phloem.

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 bottom 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 pitt, meaning the pit of a fruit.

The pith of the sola or other similar plants is used to make the pith helmet.

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

Other articles related to "pith":

Pith Helmet
... The pith helmet (also known as the safari helmet, sun helmet, topee, sola topee, salacot or topi) is a lightweight cloth-covered helmet made of cork ... Designed to shade the wearer's head and face from the sun, pith helmets were often worn by people of European origin in the tropics, but have also been used in ...
Modern Survivals - Modern Commercial Models of Pith Helmet
... The pith helmet has had a limited comeback in recent years, with their now novel appearance and genuine functionalility making the headdress increasingly ... (i) French pith helmet ... Like other civilian pith helmets it can be soaked in water to keep the wearer's head cool in hot weather ...
The Shnookums And Meat Funny Cartoon Show - Premise - Pith Possum: Super Dynamic Possum of Tomorrow
... A spoof of the Batman comics (not unlike Darkwing Duck, only more extreme in its spoofing) with Pith Possum (voiced by Jeff Bennett) and his sidekick Obediah the ... Pith Possum's true identity is lowly tabloid copyboy Peter Possum ... Pith Possum fights various enemies with his recurring one being a mad lumberjack named Dr ...
Durga Puja In Orissa - Local Traditions Related To Sharodiya Durga Puja/Dussehra - Maa Tara Tarini
... This oldest and famous Adi Shakti Pith is situated on the holy Taratirini hill (Purnagiri), at a distance of 30 km from Berhampur, in the state of Odisha, India ... It is believed to be the Breast Shrine (Sthana Pith) of Adi Shakti and originated from the limbs of the Corpse of Mata Sati ... Explaining the importance of this Pith ‘Brihat Samhita’ described it as the most prominent Tara Pith and also gives the geographical location of ...
Aeschynomene Aspera
... It is also known by the names Sola, Sola Pith Plant, Pith Plant, Laugauni or Netti (Tamil) ... Pith of low density from this plant is used to make hats known as pith helmets or sola topis ...

Famous quotes containing the word pith:

    So much of our time is preparation, so much is routine, and so much retrospect, that the pith of each man’s genius contracts itself to a very few hours.
    Ralph Waldo Emerson (1803–1882)

    Thus conscience does make cowards of us all,
    And thus the native hue of resolution
    Is sicklied o’er with the pale cast of thought,
    And enterprises of great pith and moment
    With this regard their currents turn awry,
    And lose the name of action.
    William Shakespeare (1564–1616)