Durio Oxleyanus Trees: Least Scaly Leaves, Scary Spines, Smelly Fruits

Summary: Durio oxleyanus trees get evergreen leaves with scaly midribs, Oxley's durians in four non-spiky orange-fruited parts and yellow flowers with long petals.

Oxley's durian (Durio oxleyanus); 13-phalanx, 14 and 15-vertical section of anther, 16-vertical section of ovary; illustration by English botanist and taxonomist M.T. Masters after a sketch by British botanist and physician Alexander Carroll Maingay (Oct. 25, 1836-Nov. 14, 1869); M.T. Masters, Journal of the Linnean Society (1875), vol. XIV, Tab. XIV: Public Domain, via Biodiversity Heritage Library

Durio oxleyanus trees articulate distribution ranges and life cycles that accord with other durian trees even though Oxley's durians are atypical among wild, woody durian plants for blunt-spined, four-sectioned, scarce-scented edible fruits.

Oxley's durians bear the common names durian beludu, durian daun, durian sukang, isu and kerontangan because of velvet-smooth flesh, evergreeness and orange-tinged pulp within tufted husks. The scientific name Durio oxleyanus (from the Malay duri, "thorn" and Latin oxleyanus, "concerning Oxley") commemorates Bengal Medical Staff Chief Thomas Oxley (May 1805-March 6, 1886). The current taxonomy descends from scientific descriptions in 1844 by William Griffith (March 4, 1810-Feb. 9, 1845) of a durian among nutmeg deliveries to Dr. Oxley.

The Oxley's durian explications entailed a specimen extracted from Penang island off coastal eastern Malaysia in 1843 by Johann Otto Voight (March 22, 1798-June 22, 1843).

The life cycles of Durio oxleyanus trees fit September through February flowers, October through January fruits and November through January seeds into evergreen, year-round foliage schedules.

Oxley's durian trees grow from germinated seeds that get transported by, or go through the digestive tracts of, fructivorous (fruit-eating) lowland rainforest Sumatran orangutans (Pongo abelii). Their seeds have 85 percent germination rates, within nine to 36 days, on clay-rich, frequent-flooded, sandy-soiled, well-drained hillsides up through 2,132.55-foot (650-meter) altitudes above sea level. Four-month-old, 23.62-inch- (600-millimeter-) tall seedlings incur mature 131.23- to 164.04-foot (40- to 50-meter) heights with first branches 98.42 feet (30 meters) above 9.84-foot- (3-meter-) tall buttresses.

Durio oxleyanus trees juggle 59.06- to 78.74-inch (1,500- to 2,000-millimeter) diameter, 17.64- to 35.28-ounce (500- to 1,000-gram) four-sectioned, not five-segmented, Oxley's durian fruits atop older branches.

Oxley's durian husks keep blunt, broad, green, pyramid-shaped, semi-curved spines on the outer surfaces of four weak-seamed sections whose interiors each keep one to two seeds.

Oxley's durian fruits, as the least sticky-fleshed and tortoise durians (Durio testudinarum) as most sticky-fleshed of nine edible durians, look like palm-sized, orange-yellow-tinged, smooth-textured white-gray-green globes. The Malvaceae mallow family member maintains the smoothness of creamy textures and sweetness of powdered sugar without the fetid, musky smells of many other edible durians. They net orange-yellows from 1-inch (25.4-millimeter) diameter yellow flowers with five sepals longer than five petals; and numerous black-bordered anther-topped filaments amid four- to five-stamened bundles.

Durio oxleyanus trees offer blunt-edged, oblong, round-based evergreen leaves with hairless uppersides; hairy undersides; and, atypical of edible durian tree shoots, scaly surfaces only on midribs.

Oxley's durian fruit trees prevail in soil pHs and temperatures respectively between 6 and 7 and 77 and 86 degrees Fahrenheit (25 and 30 degrees Celsius).

Durio oxleyanus trees queue up in mixed-species, moist, nutrient-rich dipterocarp ("two-winged fruit," from the Greek δίς, dís, "twice"; πτερόν, pterón, "wing"; and καρπός, karpós, "fruit") forests. They require 59.06- to 78.74-inch (1,500- to 2,000-millimeter) annual rainfall for not-too-dry, not-too-waterlogged woody layering of pink- to red-brown heartwood and red-, white- to yellow-brown sapwood. Oxley's durian-friendly environments serve local and regional agro-industrial, culinary, herbal, manufacturing and wood-working sectors with containers, frames, fuel and furniture; and edible fruits, leaves and seeds.

Durio oxleyanus trees turn up among taller edible-fruited durian species even as they turn out atypically four-sectioned, scentless, spikeless fruits and unscented flowers, foliage and wood.

The Sumatran orangutan (Pongo abelii) likes to feed on Oxley's durian (Durio oxleyanus); young Sumatran orangutan in Gunung Leuser National Park, Bukit Lawang, North Sumatra province, northwestern Sumatra; May 2007: Michaël Catanzariti, CC BY SA 3.0 Unported, via Wikimedia Commons

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Oxley's durian (Durio oxleyanus); illustration by English botanist and taxonomist M.T. Masters after a sketch by British botanist and physician Alexander Carroll Maingay (Oct. 25, 1836-Nov. 14, 1869); 13-phalanx, 14-vertical section of anther, 15-another vertical section of anther, 16-vertical section of ovary; M.T. Masters, Journal of the Linnean Society (1875), vol. XIV, Tab. XIV: Public Domain, via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/238423

The Sumatran orangutan (Pongo abelii) likes to feed on Oxley's durian (Durio oxleyanus); young Sumatran orangutan in Gunung Leuser National Park, Bukit Lawang, North Sumatra province, northwestern Sumatra; May 2007: Michaël Catanzariti, CC BY SA 3.0 Unported, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Young_orang_utan.JPG

For further information:

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Masters, Maxwell T. 1875. "Order XXVI. Malvaceae: 3.D. Oxleyanus, Griff. Notul. iv. 531." In: J.D. (Joseph Dalton) Hooker, The Flora of British India, vol. I Ranunculaceae to Sapindaceae: 351. London, England: L. Reeve & Co.
Available via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/354261

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Subhadrabandhu, Suranant; and Saichol Ketsa. 2001. Durian: King of Tropical Fruit. CABI (Centre for Agriculture and Bioscience International).