Guayule

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Guayule
Parthenium argentatum (USDA) .jpg

Guayule ( Parthenium argentatum )

Systematics
Order : Astern-like (Asterales)
Family : Daisy family (Asteraceae)
Subfamily : Asteroideae
Tribe : Heliantheae
Genre : Parthenium
Type : Guayule
Scientific name
Parthenium argentatum
A.Gray

The guayule or Mexican rubber plant ( Parthenium argentatum ) is a species of the sunflower family (Asteraceae). Due to its high milky sap content, it is used as one of the few non-tropical rubber plants.

The name Guayule comes from the Nahuatl cuauh-olli for " wooden rubber, rubber tree".

description

illustration

The drought-resistant guayule grows as a densely branched, up to 120 cm high, perennial shrub or dwarf tree with a strong tap root. The taproot can reach several meters deep and it forms extensive side roots. The young twigs and inflorescence stalks are light green, later light brown and fine-haired. The bark of fully grown trunks and branches is flat-cracked and gray-brown. When fully grown, the guayule forms a round and dense crown.

The stalked and lanceolate to obscure or spatulate, pale green leaves are 15-25 (-40+) × 6-15 (-25+) mm in size. The tip is pointed to rounded, the leaf margin is fully or irregularly serrated to slightly lobed. The leaves are above and below white-grayish fine-bristled (gray-tomentose). The base of the leaf is partly sloping. The leaves are spirally or rarely whorled and arranged opposite.

There are three to five or more stalked flowers in a long-stalked (up to 20 cm), one-sided and zymous, compound inflorescence . If there is plenty of water, the inflorescences spread apart. When water is scarce, however, the flower stalks remain very short and there may be no or stunted flowers.

In the 5 mm wide flower heads , only the five whitish, female ray florets produce fruits , while the greenish, hermaphroditic but functionally male tubular florets (disc florets) do not produce any fruits. In the flower head there are ten, five each in two circles, greenish, fine-haired bracts (phyllaria). The five ray-flowers are each fused with a bract of the basket and have a protruding tongue. The 20–30 tubular flowers sit in a bag-like, densely hairy bract (scale). They have a five-lobed corolla and five tubular stamens that have grown together and an abortive pistil .

The ray florets are each fused with two tubular flowers and a husk to a "Achänenkomplex" the short stylus has a two-lobed stigma. When it is ripe, the whole achene complex is thrown off; this is used for the seeds to spread through wind and water . The remaining disc flowers, d. H. all but ten remain attached to each other and fall off as a shrunken, conical mass together with the remaining, persistent five bracts of the flower head. After flowering, the dead stalks will remain visible above the plant's foliage, creating a striking appearance.

2.5-3 mm in size, egg-shaped and on one side flattened, light brownish achenes (Cypselas) with a very short pappus and a double seed coat (Tegmen, Testa) are formed. The testa is thin and soft, the thin tegmen is harder.

The guayule is pollinated by wind and various insects such as bees, bed bugs and beetles.

The chromosome number is 2n = 36.

distribution

The guayule is common in the semi-desert regions of northern and central Mexico in the states of Zacatecas , Coahuila , Chihuahua , San Luis Potosí , Nuevo León and Tamaulipas as well as in the southern US states of Texas and New Mexico .

ingredients

The plant accumulates large amounts of milky sap (latex) in the parenchymal cells of the stem and branches and roots, but only a little in the leaves. The latex is here in isolated milk sap cells that are scattered between the other cells and have no connection with one another. The rubber cannot be obtained by tapping it because no tubular milk tubes or vessels are formed.

Use as a rubber plant

Experimentally made products made from guayule rubber

The guayule is used as a rubber plant because of its high latex content, in contrast to the rubber tree ( Hevea brasiliensis ). The guayule rubber is a polymer of up to 6,000 isoprene units, similar to that of the rubber tree, the polyisoprene are also cis -configured here, the rubber content of the plant is usually 5–7% of the total mass, but can also be up to to 17%. When the guayule rubber is extracted, resin is also a by-product .

Historically, Guayule was particularly important during the Second World War , when the United States was cut off from rubber exports from Southeast Asia . At that time it was also grown on a trial basis in the Soviet Union . Since guayule has a much lower allergenic effect ( latex allergy ) in contrast to the para-rubber of the rubber tree , interest in guayule rubber as a renewable raw material has increased again in recent years .

The antiallergic qualities lie in the different proteins as well as the much lower protein content of the guayule rubber and the hydrophobicity of the proteins, which means that they are firmly connected to the rubber phase of the latex product.

It is mainly used to manufacture products that come into direct contact with the skin, especially mattresses, rubber gloves and other hygiene products. In April 2008, examination gloves from Yulex Corporation , USA, were the first product for medical use in the United States to be approved by the Food and Drug Administration , making natural "Yulex rubber" the only material that met the safety requirements for natural latex products based on protein content. Lately tires made from guayule rubber have also been produced.

Extraction

To obtain the rubber, the entire plant is harvested and ground, then the latex is washed out. Vulcanization with sulfur causes the isoprene chains to be irregularly linked and thus cross- linked to form an elastic rubber .

Taxonomy

The guayule was first discovered in Texas in 1852 by the North American doctor and botanist John Milton Bigelow . It was first described by Asa Gray a few years later in Torr. Bot. Mex. Bound. II, 1859, p. 86.

literature

  • Parthenium argentatum in the Flora of North America. Vol. 21.
  • Ernst Artschwager: Contribution to the Morphology and Anatomy of Guayule (Parthenium argentatum). USDA Technical Bulletin No. 842, 1943, pp. 1–33, online (PDF; 2.2 MB) at AgEcon Search, accessed on January 12, 2018.
  • Bayard Louis Hammond, Loren George Polhamus: Research on Guayule (Parthenium Argentatum), 1942–1959. USDA Technical Bulletin No. 1327, 1965.
  • Francis E. Lloyd: Guayule (Parthenium argentatum Gray). Carnegie Institution, Washington 1911, online at babel.hathitrust.org, accessed January 13, 2018.
  • Parthenium argentatum at Tropicos.org. Missouri Botanical Garden, St. Louis.

Web links

Commons : Guayule  - album with pictures, videos and audio files

Individual evidence

  1. ^ William Bright: Native American Placenames of the Southwest. Univ. of Oklahoma Press, 2013, ISBN 978-0-8061-2444-5 , p. 36.
  2. ^ A b c Siegfried Danert, Franz Fukarek: Urania plant kingdom . Volume 4: Flowering Plants 2 , Urania-Verlag, Leipzig 1994, ISBN 3-332-00497-2 , p. 338.
  3. ^ Bayard Louis Hammond, Loren George Polhamus: p. 11.
  4. ^ MG Gilliland, J. van Staden: Cyclic patterns of growth and rubber deposition in guayule Parthenium argentatum. Suggestions for a management program. In: South African Journal of Plant and Soil. 3 (1), 1986, pp. 21-26, doi : 10.1080 / 02571862.1986.10634180 , online (PDF; 1.4 MB) at Taylor & Francis Online, accessed January 12, 2018.
  5. ↑ Ernst Artschwager:
  6. ^ Ray F. Evert: Esau's Plant Anatomy. De Gruyter, 2006, ISBN 978-3-11-020592-3 , p. 454.
  7. ↑ a b Guayule useful plant database at Marburg University.
  8. ^ Diana Jasso Cantú, José Luis Angulo Sánchez, Raúl Rodriguez García: Identification of Guayule Regions in Northern Mexico, Based on Rubber Yield and Coproducts Quality . In: J. Janick (Ed.): Progress in new crops. ASHS Press, Alexandria, VA, pp. 336-339.
  9. ↑ Heinz. A. Hoppe: Drug science. Volume 1: Angiosperms , 8th edition, De Gruyter, 1975, ISBN 3-11-003849-8 , p. 801.
  10. ↑ What are some of the similarities / differences between Guayule latex and natural rubber latex? at American Latex Allergy Ass., accessed January 13, 2018.
  11. ↑ FDA approves first medical device made from natural Yulex (R) rubber . Press release Yulex Corporation, April 24, 2008.
  12. ↑ Bridgestone produces its first tires from Guayule natural rubber on bridgestone.ch, accessed on January 12, 2018.