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IAWA Journal, Vol. 15 (4), 1994: 425-437 FORMATION OF EBONY AND STREAKED WOODS by W.E. Hillis 1 and Soenardi P.2 Summary Sampies of 175 Diospyros species were wood of fine texture, uniform structure and examined with 27 containing some ebonised high air-dry density. They are ptovided by a wood which was rarely uniformly jet black. few Diospyros species and in earlier times Ebony is commonly composed of aseries of also by African blackwood or Senegal ebony axial and alternating black and paler streaks, (Dalbergia melanoxylon) which has a greater often in characteristic patterns as in D. celebi­ stability. Continued use over the centuries has ca. Large amounts of black non-structural led to a serious depletion of resources. The deposits first appear in vessels, then fibres, demand for ebony continues, despite its high and the origin of these materials could not be price, and present supplies may last for only found. Deposits were absent from the axial about 25 years. Research into plantation de­ and ray parenchyma of the paler streaks. Crys­ velopment has commenced (Sidiyasa 1989) tals were present in some species. Fungi have and plots of up to 50 years in age have been been detected in tissues adjacent to ebonised established. Development of procedures to wood which appears to be formed differently increase ebony formation is needed. from normal heartwood. Existing information covers the presence Possible mechanisms for the formation of or absence of ebony in a particular species ebony and other streaked woods are discussed which appears not to be influenced by age, to assist the maintenance of resources of these girth or environment. Studies on the factors high value, decorative woods. We propose influencing and increasing the formation of the black deposits found in the streaks in some the black cellu1ar contents in Diospyros are Diospyros species, and in ebony, are formed becoming increasingly difficult because of the as a response to invasion, by appropriate fun­ severe and increasing shortage of experi­ gi, from the roots affecting firstly the con­ mental material. Perhaps the 1argest remain­ tents of the vessels. ing resource is that of Macassar Ebony from Key words: Ebony, Diospyros spp., streak­ D. celebica in Sulawesi (formerly Ce1ebes), ed woods, cellular deposits, fungi. Indonesia. This paper presents information on the Introduction unique formation of ebony in Diospyros. It Almost 4000 years aga ebony carvings also brings attention to regularly formed and furniture were placed in Egyptian tombs. streaks in the heartwood of a range of species, About 1000 years later the Ethiopians were a feature which has received little scientific sending tributes of ebony logs to Persia and attention. ancient Indian Kings were using ebony carv­ About 500 Diospyros species are reported ings. In more recent tim es ebony has been to exist (e.g. Mabbedey 1989) growing in used not only in specialised furniture and localised regions in warm and tropical cli­ carvings but also as non-resonant wood for mates. In recent times the ebony containing musical instruments, piano keys etc. There species developed best in the Indo-Ma1ayan are several types of this black, hard he art- region. The species are slow growing and 1) CSIRO, Division of Forest Products, Private Bag 10, Rosebank MDC, Clayton, Vic 3169, Australia. 2) Gadjah Mada University, Faculty ofForestry, Yogyakarta, Indonesia. Downloaded from Brill.com09/29/2021 08:35:13AM via free access 426 IAWA Journal, VoL 15 (4), 1994 ~~~~~~~~~--~~--~~---~~~~--~--- Downloaded from Brill.com09/29/2021 08:35:13AM via free access Hillis & Soenardi P. - Ebony and streaked woods 427 exist either as small trees (2.5-4.5 m high, The ebonies from D. eben um (Sri Lanka), D. 0.6 m bole diarn.) or medium sized (15-24 m reticulata (Mauritius), D. crassifolia (Africa), high, 0.6-0.75 m bole diarn.) but rarely as and D. mollis (Thailand) (Fig. 1) for example tall trees (61 m). They are similar botanically are mainly uniformly jet black but may occa­ and particularly in their wood anatomy (which sionally have greenish black streaks. The de­ is characteristic for the genus) so that they are velopment of heartwood frequently varies difficult to distinguish (Wright 1904; Purka­ markedly within a species and often in neigh­ yastha 1982). Growth rings are inconspicu­ bouring trees; injury of sapwood can result in ous or obscure; the close grained, diffuse-por­ black coloured wood (Fig. 1). Before severe ous wood is hard. The sapwood of various exploitation began the bole of D. eben um trees species is less hard and significantly less then measured between 28-56 cm diameter heavy (60-70 kg/m 3) than the heartwood and contained 23% by weight heartwood (up to 90-110 kg/m 3). Sapwood, which is (true ebony), and D. melanoxylon trees were most commonly the largest, or total woody 27-32 cm diameter containing 11-12 cm portion of the tree, varies in amount within heartwood (known as Coromandel). Even in and between species. It is considerably paler large trees of D. quaesita the heartwood (Ca­ and distinct from the heartwood and consid­ lamander) was sometimes absent (Wright erably less durable (Fig. 1). The colourless, 19(4). There is no apparent rcason why heart­ pink or light-tan sapwood can contain iso­ wood is formed in a species or why the pro­ lated black streaks which can sometimes be portion varies. This study was undertaken to traced to an injury (e. g. Burkill 1935; Met­ ascertain the factors responsible for the for­ calfe & Chalk 1950; Wright 1904). mation of highly valuable ebony. Diospyros species can be classified by the heartwood which, if present, is abruptly Materials and Methods formed from the sapwood and has an irregu­ Over 276 sam pies from 93 named Diospy­ lar outline which does not always follow the ras species and from 82 unnamed species in growth rings (Fig. 1). The four classes are the H. E. Dadswell Memorial Wood Collection based on those of Gamble (1922; see also (FPAw) were examined for the presencc of Pearson & Brown 1932) in which the hcart­ ebony. In addition 27 sampies from 10 Maba wood is: species (in the same family of Ebenaceae) were examined. Sam pies from the following spe­ a) wholly black, or only slightly thinly streak­ cies contained ebony or black wood: D. buxi­ ed with brown or dark grey, extending for folia Hiem, D. celebica Bakh., D. crassiflora a considerable distance axially; Hiem, D. dendo Wehrh., D. discolor Willd., b) characteristically of black streaks (some­ D. ebenaster Retz., D. eben um Koenig, D. times mottled) of varying widths in a elmeri Merr., D. ferrea Bakh., D. ferrea var. brown or grey wood; humilis Bakh., D. hebecarpa Benth., D. lan­ c) a very small proportion of black streaks in cifolia Roxb., D. latisepala Ridley, D. lolin a brown-grey or grey wood; Bakh., D. macassar A. Chev., D. marmorata d) absent and the wood is red, colourless, Park., D. mespiliformis Hochst., D. mollis grey, or/to yellowish. Griff., D. montana Roxb., D. mun A. Chev., Only about 30 species belong to the first two D. ovalifolia Wright, D. papuana Vail, D. pen­ classes which form significant amounts of tamera F. Muel!., D. philippinensis Adams, ebony. Of the 90-100 species in Indonesia D. pilosanthera Blanco, D. retropaeta Bakh., only 7 produce ebony (Surianegara 1967). D. rigida Hiern, D. rubra, D. sogeriensis Fig. 1. Diospyros mollis: Jet black heartwood, larval holes in sapwood, black band interior to decayed wood and injury. - Fig. 2. Diospyros celebica: From sapwood to pith, with black and brown streaks and empty rays (arrow) in the latter. - Fig. 3. Diospyros celebica: Sapwood on the right containing black knots, heartwood with streaks in a marbled pattern. Downloaded from Brill.com09/29/2021 08:35:13AM via free access 428 IAWA Journal, VoL 15 (4), 1994 Bakh., D . texana Schiede, D. tesselaria. Sev­ ery inwards to the heartwood of these trees. eral species had pale brown streaks in the Each batch of sticks was soaked separately in sapwood but were not examined further. Eb­ a 1% silver nitrate solution for 3 minutes, onised wood was found only in specimens of rinsed with sterile water, then cultured sepa­ Maba buxifolia Pers., M. geminata R. Br., and rately in sterile petri dishes of malt ag ar me­ M. reticulata. dium in a 24°C room. In addition a total of 49 Three to four specimens of most species cores were taken at about 0.5 m above ground were examined but the number was too small level from plantation trees growing in West for representative observations. Java and pretreated with Carnoy's fluid be­ In addition, artefacts from West and East fore despatch. The age of 34 trees was 26 Africa, India, Sri Lanka, Indonesia, Philip­ years and had a d. b. h. of 23-46 cm; the pines and Papua New Guinea have been ex­ other trees with ages of 14-36 years had a amined. d. b. h. within these limits. Three trees of D. celebica from the Maros Dried sampies of D. celebica and D. tessel­ Forest Reserve near Ujung Pandang in south­ aris were highly polished using a Reichert­ ern Sulawesi were examined. The trees were Jung, Polycut E, sledge microtome with a cross-cut into 50-100 cm lengths and then Diamond Ultramiller attachment and then cut longitudinally through the pith. examined with a Reichert-Jung Polyvar Met Tree A of about 11 cm diameter at the base Darkfield epi-illumination. and about 10 m tall contained sapwood apart from sm all sporadic ebonised spots behind Results branch stubs.

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