Narrow-leaved Paperbark Tree (Melaleuca alternifolia)

 This article by Jerry Cates was first published on 23 October 2015, and revised last on 2 April 2016. © Budsinthenews Vol. 6:12.

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Narrowleaf paperbark tree (Melaleuca alternifolia), leaves and blossoms.

Narrow-leaved paperbark tree (Melaleuca alternifolia), leaves and blossoms.

The narrow-leaved paperbark tree (Melaleuca alternifolia), is native to Australia and is found in southeast Queensland and the north coast and adjacent ranges of New South Wales. There it grows along streams and on swampy flats. Where it thrives it is often the dominant species.

A relatively small tree, it grows to about 7 meters (20 feet). It is characterized by a brushy crown and thin, white, paper-like bark. The oil-rich leaves, which are needle-like and shaped much like the needles of the rosemary herb, measure 10–35 millimeters (0.4–1 inch) long, 1 millimeter (0.04 inch) wide.

Oil derived from the leaves of this tree is commonly known as tea tree oil. This oil has been used medicinally by Australian natives for many centuries, and according to legend, for thousands of years. Various reports, some in conflict, chronicle how Captain James Cook and his botanist, Joseph Banks, discovered the native use of tea tree oil and how they and the sailors on Cook’s vessel, the British ship H.M.S. Endeavor, to prevent scurvy and heal wounds.

Cook’s first voyage, in search of the continent of “Terra Australis” led him to find and map the coast of New Zealand. Soon afterward, on April 19, 1770, he sailed to the southeastern coast of Australia, becoming the first European of record to have done so.

When Cook came ashore at what he named, “Botany Bay,” he was met by members of a native tribe, the Gweagal, and began to explore the Australian continent by traveling north along the coast of what is now known as New South Wales. Along the way natives introduced Cook to the medicinal value of a species of tree, whose leaves exuded an aromatic oil. Cook had his crew brew a tea from the leaves, in hopes of curing and preventing scurvy. The experiment worked, and regular use of the tea commenced. It was from this practice that the name “Tea Tree” came into being.

Since then, the use of tea tree oil as a medicine has alternately waxed and waned. Today it has again become popular, and now is available worldwide. Common uses of tea tree oil reflect its antiseptic and anti-inflammatory properties. In recent years the nature of the antimicrobial and anti-inflammatory activities of the oil and its components, as well as their clinical efficacies, have been studied in even greater depth.

Scientific analyses have shown that tea tree oil is composed of terpene hydrocarbons, mainly monoterpenes, sesquiterpenes, and their associated alcohols. Terpenes, which are volatile, aromatic hydrocarbons, may be considered polymers of isoprene, with the formula C5H8. Though early reports on the composition of tea tree oil found 12, 21, and 48 distinct components, a more complete analysis conducted in 1989 by Brophy et al., reported as many as 100 components, ranked according to their ranges of concentrations

Flowers, which emerge for a short period in the spring and early summer, form fluffy white masses of spikes that measure 3–5 centimeters (1–2 inches) long. Scattered on the branches are small cup-shaped woody fruits, 2–3 millimeters (0.08–0.1 inch) in diameter.

Joseph Maiden and Ernst Betche first described this plant in 1905, giving it the taxonomical name Melaleuca linariifolia var. alternifolia, applying the specific name linariifolia to establish their belief that they were describing a variety of M. linariifolia (whose leaves were similar to those of trees in the genus Linaria), rather than a new species.  The fact, however, that leaves of M. linariifolia occur in alternating pairs on each side of the stem, while those of M. alternifolia alternate singly on each side of the stem, suggested to many that the two trees were not varieties, but distinctly separate species. In 1925 Edwin Cheel renamed it as Melaleuca alternifolia.

The narrow-leaved paperbark tree prefers full sun placement but thrives in a variety of climates. It does well in a number of soil profiles, provided the soil is well-drained and moist.

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Taxonomy:

  • Domain: Eukaryota (yew-carr-ee-OH-tah)  — from the Greek prefix ευ (yew) = good, well, pleasing + καρυον (khar-yone) = a nut/nucleus, thus organisms whose cells contain a nucleus and other organelles within membranes.
  • (unranked): Bikonta Cavalier-Smith, 1993 (bye-KOHN-tuh) — from the Latin bis = twice/double + the Greek κοντος = a punting pole; those eukaryotic organisms within the subgroups Apusozoa, Rhizaria, Excavata, Archaeplastida, or Chromalveolata.
  • (unranked): Archaeplastida Adl et al., 2005 (ahr-kee-PLASS-tih-duh) — from the Greek αρχαιος (AHR-kee-ose) = ancient/antiquated + πλασις (PLAS-iss) = a moulding + Anglo Saxon tid = time; a major group of eukaryotes, comprised of the red algae (Rhodophyta), the green algae, and the land plants along with the freshwater unicellular algae known as glaucophytes.
  • Kingdom/Regnum: Plantae Copeland, 1956 (PLAN-tee) or Viridiplantae Cavalier-Smith, 1881 (veer-id-eye-PLAN-tee) — from the Latin planta = a green twig; the plant kingdom, consisting of multi-cellular green plants, i.e., whose cells have cellulose within their cell walls and have primary chloroplasts derived from endosymbiosis with cyanobacteria containing chlorophylls a and b and lack phycobilins..
  • (unranked): Streptophyta Jeffrey 1967 (strepp-toh-PHY-tuh) — from στρεπτος (STREP-tose) = (easily) twisted, pliant + φυτον (PHU-tawn) = a plant/tree; the land plants and the green algal group Charophyta.
  • Subkingdom: Embryophyta Engler, 1892 (imm-bree-oh-FYE-tuh) — from the Greek εμβρυον (EMM-bree-yon) + φυτον (PHU-tawn) = a plant/tree; green plants, informally known as land plants because most are terrestrial rather than aquatic, while the related green algae are primarily aquatic;
  • (unranked): Angiosperms (AN-gee-oh-spurms)/Magnoliophyta Cronquist (mag-NOH-lee-oh-fye-tuh) — from the Greek αγγειον (AUGG-ee-awn) = a vessel/pail/reservoir + σπερμα (SPUR-mah) = a seed; the flowering plants, distinguished from the gymnosperms by having flowers, endosperm within the seeds, and the production of fruits that contain the seeds;
  • (unranked): Eudicots (YEW-dee-kotts) — from the Greek prefix ευ (yew) = good, well, pleasing + δι (die/dee) = two/double + κοτυληδων (cott-ee-LEE-dun) = a cup-shaped hollow; a monophyletic clade of flowering plants previously known as tricolpates or non-magnoliid dicots, to emphasize the evolutionary divergence of tricolpat dicots from earlier, less specialized dicots; close relationships are presumed among flowering plants with tricolpate pollen grains (the grains have three colpi, or elongated apertures or furrows in the pollen grain paralleling the polar axis);
  • (unranked): Rosids — a large monophyletic clade of flowering plants comprised of some 70,000 species;
  • (unranked): Eurosids II
  • Order: Myrtales Juss. ex Eercht. & J. Presl — from the Greek μυρον (MEW-ron) = sweet oil/unguent/ perfume; an order of flowering plants comprised of nine families which, based on chloroplast DNA analyses, evolved in the mid-cretaceous period 100mya in Southeast Africa, but on the basis of nuclear DNA evolved 89-99mya in Australasia;
  • Family: Myrtaceae Juss. — from the Greek μυρσαινη (MYR-suh-ine) = the myrtle; a family of dicot plants of 130-150 genera and over 5,560 species;
  • Subfamily: Myrtoideae (merr-TOY-duh-ee)
  • Tribe: Melaleuceae (meh-luh-LEW-kuh-ee)
  • Genus: Melaleuca L. nom. cons. (meh-luh-LEW-kuh) — from the conjunction of two Greek descriptors, μελας (MEL-as) = dark/black + λευκος (lew-KOS) = white, a result of the specimen under examination having been covered in thin layers of bark blackened on their exterior surfaces by exposure to fire, while the deeper layers of the specimen’s paper-like bark were starkly white; a genus of almost 300 species of small shrubs and large trees, known commonly as paperbarks, honey-myrtles, or tea-trees (the last also being applied to species in the genus Leptospermum), with flowers in groups resembling typical bottle-brushes (elongated groupings of flowers, rather than the spherical grouping of flowers of the atypical bottle brush); most are native to Australia, others to the Malesia floristic region of the Malay peninsula and Archipelago, New Guinea, and the Bismarck Archipelago;
  • Species: M. alternifolia (awl-turr-neh-FOH-lee-uh) — a small tree with linear, smooth, soft, glandular leaves, a bush-like crown, and bark that exfoliates in thin white sheets; the leaves are crushed for use as a poultice, or distilled to produce an essential oil known commonly as tea tree oil;

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References:

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