Dysoxylum

Dysoxylum is a genus of rainforest trees and shrubs in the flowering plant family Meliaceae. About 34 species are recognised in the genus, distributed from India and southern China, through southeast Asia to New Guinea, Solomon Islands, and Australia. The name Dysoxylum derives from the Greek word ‘Dys’ meaning "bad" referring to "ill-smelling" and ‘Xylon’ meaning "wood".

Distribution
The genus ranges from the Indian subcontinent to Indochina, southern China, Malesia, New Guinea and the Solomon and Santa Cruz Islands, and northern and eastern Australia.

Eight species are native to the Indian subcontinent. 15 species are native to Indochina, and 6 are native to southern China. 13 species are native to Malesia, and seven species to Papuasia (New Guinea, the Bismarck Archipelago, and Solomon Islands) and the Santa Cruz Islands.

Four species – Dysoxylum acutangulum, D. latifolium, D. oppositifolium, and D. pumilum – are native to Australia. They grow in northwestern New South Wales, the humid east coast regions regions of Queensland including the wet tropics rainforests region of northeastern Queensland and Cape York Peninsula, and the northern parts of the Northern Territory and Western Australia.

In the Indian subcontinent, including India, Bhutan, Nepal, and Sri Lanka, large trees of the genus Dysoxylum grow naturally in forests from lowlands to mid-elevation mountains. Eight species are native to the region. D. beddomei, D. malabaricum, D. purpureum, and D. swaminathanianum are endemic to southwestern India. D. cyrtobotryum, D. gotadhora, D. grande, and D. pallens are native to the Indian subcontinent and southeast Asia.

Habitats
These trees are important components of the native tropical forests of their range, such as New Guinea and the tropical forests of northern Australia. In this region, more than forty different species grow naturally, from the lowlands to the mountains. In New Guinea, D. enantiophyllum and an undescribed taxon have records of growing up to about 3,000 m elevation.

In the forests of the region of China, India, Sri Lanka and the adjacent Himalayas including Bhutan and Nepal, about fourteen recorded different species grow naturally from the lowlands to the mountains up to 1,700 m elevation.

In India, Dysoxylum malabaricum is known by many other names such as Indian white cedar, Bili devdari, Bombay white cedar, Velley agile, Porapa, Vella agil, and Devagarige. It grows in the evergreen forest regions of Western Ghats, North Kanara, Coorg, Anaimalai Hills, and Travancore regions.

Uses
The Australian species were prized for their wood which is a rich red in colour and was widely used in the furniture trade. The common timber name for the Australian species is the rose mahogany. The New Zealand species, Kohekohe (D. spectabile), is sometimes known as New Zealand mahogany, because its wood is light, strong and polishes to a fine red colour.

Rohitukine (C16H19O5N), a chromane alkaloid, was first reported from Amoora rohituka (Roxb.) Wight & Arn. (Meliaceae) and then from D. binectariferum (aka D. gotadhora) Rohitukine exhibits both anti-inflammatory as well as immuno-modulatory properties besides acting as an anticancer compound. Rohitukine is an important precursor for the semi-synthetic derivative, flavopiridol (C21H20Cl NO5).

In India, apart from its economic importance for building and furniture making, it is an important ingredient in Ayurvedic Medicine as many species have curative qualities taken independtly or as an ingredient of a medicinal mixture. Some of the uses in Ayurveda reported are; Wood decoction of D. malabaricum to cure rheumatism and its oil is used to cure eye and ear diseases; a few species are used to cure inflammation, cardio-disorder, CNS disorder and also tumor. In Indian tradition and culture oil is extracted from the seeds Dysoxylum malabaricum, which has wide beneficial application.

Taxonomy
The genus Dysoxylum was erected in 1825 by the German-Dutch botanist Carl Ludwig Blume to accommodate some newly discovered plant species from Java. Over the years many changes were made to the genus, and by the late 20th century it was clear that Dysoxylum had become polyphyletic. A 2021 revision of the genus (which by then had come to include 94 species) confirmed the polyphyly and the authors reinstated several genera which had previously been considered synonyms of Dysoxylum – Didymocheton, Epicharis, Goniocheton, Prasoxylon, and Pseudocarapa – in order to accommodate their findings.

The authors (Holzmeyer et al.) proposed a circumscription (i.e. a concept of included species) of the genus that included 28 species, plus one subspecies. Following the publication of the 2021 paper, Plants of the World Online (POWO) revised their own circumscription of the genus to include 34 species. Of the 28 species proposed by Holzmeyer et al., only 23 are accepted by POWO, and there are 11 species included by POWO that were not proposed by Holzmeyer et al.

Species
34 species are currently accepted by Plants of the World Online.


 * Dysoxylum acutangulum
 * subsp. acutangulum – Peninsular Thailand, Malesia: Sumatra, Malay Peninsula, Borneo, Philippines
 * subsp. foveolatum – New Guinea, Solomon Is., Queensland, NT, N. Australia; Malesia: Sumatra, Java, Flores, Timor, Moluccas
 * Dysoxylum beddomei – India
 * Dysoxylum brachybotrys – Malesia: Borneo, Philippines
 * Dysoxylum carolinae – Vietnam; Malesia: Sumatra, Malay Peninsula, Borneo
 * Dysoxylum cupuliforme – south-central China (Yunnan)
 * Dysoxylum cyrtobotryum – SE Asia to Malesia: Nicobar Is., Andaman Is., Sumatra, Malay Peninsula, Borneo, Java, Bali, Flores, Philippines
 * Dysoxylum enantiophyllum – New Guinea
 * Dysoxylum flavescens – Malesia: Sumatra, Malay Peninsula, Borneo
 * Dysoxylum gotadhora – S. China, Hainan, Bhutan, India, Laos, Nepal, Thailand, Vietnam - Syn. Dysoxylum ficiforme  – India
 * Dysoxylum grande ; Synonym: D. verruculosum – NE India (Assam), S. China, Vietnam, Thailand, Hainan, Bhutan; Malesia: Sumatra, Malay Peninsula, Borneo, Philippines
 * Dysoxylum hoaense – Vietnam
 * Dysoxylum juglans – Laos, Vietnam
 * Dysoxylum kaniense – New Guinea, Solomon Is.
 * Dysoxylum latifolium – New Guinea, Solomon Is., Queensland wet tropics, Cape York, NT, Western Australia
 * Dysoxylum laxiracemosum – south-central China (southern Yunnan)
 * Dysoxylum macrocarpum – Thailand; Malesia: Sumatra, Malay Peninsula, Borneo, Sulawesi, Java, Philippines
 * Dysoxylum magnificum – SE Sumatra, Borneo
 * Dysoxylum malabaricum – Akil, India
 * Dysoxylum medogense – southeastern Tibet
 * Dysoxylum middletonianum – eastern New Guinea
 * Dysoxylum oliveri – northern Myanmar
 * Dysoxylum oppositifolium, pink mahogany – New Guinea, Solomon Is., Queensland wet tropics, Cape York, NT; Malesia incl.: Borneo, Philippines, Sumba, Flores
 * Dysoxylum pachyrhache – Borneo
 * Dysoxylum pallens – S. China, Hainan, Bhutan, Cambodia, India, Burma, Thailand
 * Dysoxylum papillosum – Peninsular Thailand; Malesia: Malay Peninsula, Borneo
 * Dysoxylum perryanum – Vietnam
 * Dysoxylum poilanei – southern Vietnam
 * Dysoxylum pumilum – Queensland wet tropics endemic
 * Dysoxylum purpureum – southern India
 * Dysoxylum quadrangulatum – Sulawesi
 * Dysoxylum randianum – New Guinea
 * Dysoxylum rubrocostatum - Vietnam
 * Dysoxylum rugulosum – Malesia: Sumatra, Malay Peninsula, Borneo
 * Dysoxylum swaminathanianum – India (Kerala)

Formerly placed here

 * Didymocheton aliquantulus (as Dysoxylum aliquantulum )
 * Didymocheton aneityensis (as Dysoxylum aneityense )
 * Didymocheton annae (as Dysoxylum annae )
 * Didymocheton bijugus (Labill.) Holzmeyer & Mabb. (as Dysoxylum bijugum, D. leratianum , D. parvifolium , D. patersonianum , and D. unijugum )
 * Didymocheton boridianus (as Dysoxylum boridianum  )
 * Didymocheton canalensis (as Dysoxylum canalense )
 * Didymocheton fraserianus (as Dysoxylum becklerianum, D. fraserianum , D. lessertianum , and D. ptychocarpum )
 * Didymocheton gaudichaudianus (as Dysoxylum albiflorum, D. amooroides , D. bakerarum , D. betchei , D. blancoi , D. decandrum , D. gaudichaudianum , D. intermedium , D. macrophyllum , D. maota , D. otophorum , D. pubescens , D. quaifei , D. rufum var. glabrescens , D. salutare , D. spanoghei , and D. vestitum )
 * Didymocheton hornei (as Dysoxylum hornei )
 * Didymocheton huntii (as Dysoxylum huntii )
 * Didymocheton kouiriensis (as Dysoxylum kouiriense )
 * Didymocheton lenticellaris (as Dysoxylum lenticellare )
 * Didymocheton loureiroi (as Dysoxylum loureiroi )
 * Didymocheton macranthus (as Dysoxylum macranthum )
 * Didymocheton macrostachyus (as Dysoxylum macrostachyum )
 * Didymocheton minutiflorus (as Dysoxylum minutiflorum )
 * Didymocheton mollis (as Dysoxylum molle, D. mollissimum subsp. molle , and Dysoxylum velutinum )
 * Didymocheton mollissimus (as D. alliarum, D. filicifolium , D. floribundum , D. hainanense , D. hainanense var. glaberrimum , D. hamiltonii , D. leptorrhachis , D. mollissimum , D. octandrum , D. schizochitoides , and D. teysmannii )
 * Didymocheton muelleri (as Dysoxylum muelleri )
 * Didymocheton multijugus (as Dysoxylum seemannii )
 * Didymocheton myriandrus (as Dysoxylum myriandrum )
 * Didymocheton nutans (as Dysoxylum nutans  )
 * Didymocheton pachyphyllus (as Dysoxylum pachyphyllum )
 * Didymocheton pachypodus (as Dysoxylum pachypodum )
 * Didymocheton papuanus (as Dysoxylum micranthum  and D. papuanum  )
 * Didymocheton pauciflorus (as Dysoxylum biflorum, D. laxum , and D. pauciflorum )
 * Didymocheton pettigrewianus (as Dysoxylum pettigrewianum  )
 * Didymocheton phaeotrichus (as Dysoxylum phaeotrichum  )
 * Didymocheton roseus (as Dysoxylum comptonii, D. coriaceum , D. couveleense , D. francii , D. gamosepalum , D. pancheri , D. pancheri var. subsessilifolium , D. robertsii  D. roseum , and Dysoxylum vieillardii )
 * Didymocheton rufescens (as Dysoxylum rufescens )
 * Didymocheton rufus (as Dysoxylum rufum )
 * Didymocheton sessilis (as Dysoxylum sessile )
 * Didymocheton setosus (as Dysoxylum setosum  )
 * Didymocheton sparsiflorus ) (as Dysoxylum sparsiflorum )
 * Didymocheton spectabilis – kohekohe (syn. Dysoxylum spectabile )
 * Didymocheton stellatopuberulus (as Dysoxylum carrii, D. hirtum , and D. stellatopuberulum  )
 * Didymocheton tenuiflorus (as Dysoxylum tenuiflorum )
 * Didymocheton tongensis (as Dysoxylum tongense  )
 * Didymocheton variabilis (as Dysoxylum variabile  )
 * Epicharis alata (as Dysoxylum alatum )
 * Epicharis brevipanicula (C.DC.) Hauenschild & Mabb. (as Dysoxylum brevipaniculum )
 * Epicharis cumingiana (as Dysoxylum cumingianum )
 * Epicharis cuneata (as Dysoxylum angustifoliolum, D. beccarianum , D. cauliflorum , D. cuneatum , D. foxworthyi )
 * Epicharis densiflora – Bali floral emblem, known as majegau (as Dysoxylum densiflorum )
 * Epicharis gillespieana (as Dysoxylum gillespieanum )
 * Epicharis parasitica (as Dysoxylum brachypodum, D. callianthum , D. caulostachyum , D. densevestitum , D. fissum , D. fragrans , D. glochidioides , D. leytense , D. loheri , D. longicalicinum , D. longiflorum , D. longipetalum , D. megalanthum , D. novoguineeuse , D. parasiticum ,   D. ramiflorum , D. richardsonianum , D. robinsonii , D. roemeri , D. rumphii , D. schiffneri , D. sericeum , and D. speciosum )
 * Goniocheton arborescens (as Dysoxylum arborescens   )
 * Goniocheton brassii (as Dysoxylum brassii )
 * Goniocheton lenticellatus (as Dysoxylum lenticellatum )
 * Prasoxylon alliaceum (as Dysoxylum alliaceum )
 * Prasoxylon angustifolium (as Dysoxylum angustifolium  )
 * Prasoxylon excelsum (as Dysoxylum excelsum )
 * Prasoxylon hapalanthum (as Dysoxylum hapalanthum )
 * Prasoxylon hongkongense (Dysoxylum hongkongense )
 * Prasoxylon klanderi (as Dysoxylum klanderi )
 * Prasoxylon rigidum (as Dysoxylum rigidum  )
 * Pseudocarapa championii (as Dysoxylum championii )
 * Pseudocarapa crassa (as Dysoxylum crassum )
 * Pseudocarapa dumosa (as Dysoxylum dumosum )
 * Pseudocarapa inopinata (as Dysoxylum inopinatum )
 * Pseudocarapa yunzaingensis (as Dysoxylum yunzaingense )

Cited works