| Rainbow eucalyptus | |
|---|---|
 | |
| Looking up from the trunk to treetop of aEucalyptus deglupta | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Rosids |
| Order: | Myrtales |
| Family: | Myrtaceae |
| Genus: | Eucalyptus |
| Species: | E. deglupta |
| Binomial name | |
| Eucalyptus deglupta | |
| Synonyms[2] | |
Eucalyptus deglupta is a species of tall tree, commonly known as therainbow eucalyptus,[3]Mindanao gum, orrainbow gum[4] that is native to thePhilippines,Indonesia,Timor Leste andPapua New Guinea. It is the onlyEucalyptus species that usually lives in rainforest, with a natural range that extends into the Northern Hemisphere. It is characterized by multi-coloured bark.
Eucalyptus deglupta is a fast-growing tree that typically reaches a height of 60–75 m (197–246 ft) with the trunk up to 240 cm (94 in) in diameter and withbuttresses up to 4 m (13 ft) high. It has smooth, orange-tinted bark that sheds in strips, revealing streaks of pale green, red, orange, grey, and purplish brown. The branchlets are roughly square in cross section, often with narrow wings on the corners. The leaves are arranged in opposite pairs, mostly 75–150 mm (3–6 in) long and 50–75 mm (2–3 in) wide on a shortpetiole. The flower buds are arranged in a branchinginflorescence in leafaxils, or on the end of branchlets, each branch with groups of seven buds, the individual buds on apedicel about 5 mm (3⁄16 in) long. Mature buds are pale green or cream-coloured, roughly spherical in shape and2–5 mm (1⁄16–3⁄16 in) in diameter with a hemisphericaloperculum with a small point on the top. Flowering time depends on location, and thestamens that give the flowers their colour are white and pale yellow. The fruit is a woody, brown, hemisphericalcapsule about3–5 mm (1⁄8–3⁄16 in) long and wide, with three or four valves extending beyond the rim of the fruit. Each cell of the fruit contains between three and twelve minute brown seeds, each with a small wing.[5][6]
Eucalyptus deglupta was first formally described in 1850 byCarl Ludwig Blume who published the description in his bookMuseum Botanicum Lugduno-Batavum sive stirpium Exoticarum, Novarum vel Minus Cognitarum ex Vivis aut Siccis Brevis Expositio et Descriptio from material collected in mountain forests inthe Celebes.[2][7] Thespecific epithet (deglupta) is aLatin word meaning "peeled off, husked or shelled".[8]
In 1914,Adolph Daniel Edward Elmer describedEugenia binacag inLeaflets of Philippine Botany, thespecific epithetbinacag a local name for the tree,[9] but in 1915 changed the name toEucalyptus binacag.[10] However, the species had already been namedE. deglupta byBlume in 1850 andE. binacag is now regarded as asynonym.[2]
In 1854,Asa Gray describedEucalyptus multiflora inUnited States Exploring Expedition - Botany, Phanerogamia from an unpublished description byLouis Claude Richard,[11][12] but is anomen illegitimum because the name was already in use for a different species (Eucalyptus multifloraPoir.) now known asEucalyptus robusta.[13]Eucalyptus multiflora is also a synonym ofE. deglupta.[2]
Eucalyptus sarassa andE. versicolor, first described in 1850 by Blume in his bookMuseum botanicum Lugduno-Batavum,[14] andE. schlechteri first described byLudwig Diels inAdolf Engler's bookBotanische Jahrbücher für Systematik, Pflanzengeschichte und Pflanzengeographie[15] are also considered to be synonyms ofE. deglupta byPlants of the World Online.[2]
The rainbow eucalyptus grows in lowland and lower montane rainforest from sea level to altitudes of up to 1,800 m (5,900 ft). It is native to Indonesia, Timor Leste , Papua New Guinea, and the Philippines, but has been widely planted in many other countries.[2]
The populations of this species are severely fragmented in the wild and the overall population is decreasing. Over the last 210 years it is estimated that there has been a 30% decline of the overall population. TheInternational Union for the Conservation of Nature listedE. deglupta as avulnerable species in 2019.[1]
This tree is grown widely around the world in treeplantations, mainly forpulpwood used in making white paper. It is the dominant species used for pulpwood plantations in thePhilippines.[16][17]
E. deglupta are commonly planted as ornamental trees in frost-free climates such as Hawaii, Southern California, Texas and Florida.[18] It is planted in at least three locations in coastal Los Angeles County, including Santa Monica and San Marino at the Huntington Botanical Garden. These trees were still growing, but relatively young at approximately 30–40 years in 1988, at the UCLA Botanic Garden and as a LA City street tree.[19]
If grown from seed, the temperature should be around 68–72 °F (20–22 °C).[20] Plants can be grown from cuttings of trees younger than 5 years old. Once a tree reaches 5 years of age, root inhibition prevents the generation of roots from cuttings.[21] It thrives in rich medium-to-wet soil in full sun and is intolerant of frost.[22] In botanical gardens such asFairchild Tropical Botanic Garden in Florida, the tree does show the intense colour range as seen in the tree's normal range.[23][24]
