IAWA Journal, Vol. 15 (4), 1994: 425-437

FORMATION OF AND STREAKED WOODS

by

W.E. Hillis 1 and Soenardi P.2

Summary Sampies of 175 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.

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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 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 ) 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.

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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. Tree B of about 23 cm diam• eter and about 18 m tall contained an ebonised Appearance innerwood of ab out 9 cm diameter extending A large number of Diospyros species con• about 70 cm above ground level. The reddish tained only sapwood and even with D. cele• intermediate wood between this region and bica growing in Sulawesi heartwood forma• the sapwood was 2-5 cm wide. Ebonised tion was not usual. Most of the specimens spots were observed behind branch stubs and which contained ebony possessed it in a small centre-rot at the butt. Tree C of about 39 cm proportion of the cross sections. It was 10- diameter at the base and 24 m tall contained cated inside an irregular or undulating circular an ebonised innerwood of about 15 cm diam• periphery which changed direction radially eter and a length of about 6 m above ground and longitudinally (Figs. 1-3) as indicative level. The rest of the stern showed similar pat• of pathological origin. A few specimens had terns to those in tree B. radial (sometimes tangential) cracks surround• The strip 2 cm wide cut across a 3 cm ed by a black border (1-9 mm wide) and thick disc from tree C passed through the often with a thin decayed interior (e.g. D. intermediate wood (2-5 cm wide) and the ovalijolia). Some specimens showed black pith. The strip was cut into 3 x 2 x cm 1 spots or small zones irregularly distributed in blocks and the moisture content determined the sapwood, and they appeared longitudinal• within a few days of collection of the main ly as streaks or strands. These small zones co• sampie. alesced with heartwood as it enlarges without Several specimens of intermediate wood leaving included sapwood. Black zones are from D. celebica in Sulawesi were treated associated with knots, branch stubs, decay, with Carnoy's fluid in the field and then stain• insect holes or injury (as in D. mallis; Fig. 1). ed with Aceto-carmine and Leuco-basic fuch• Some freshly cut D. celebica sampies had sin in the laboratory. Delays during transit a wide reddish, pale-brown or yellow inter• from a distant location prevented the detec• mediate wood. This zone was difficult to de• tion of living cells in the intermediate wood tect in dried sampIes of different species. It although starch was present. was absent in cross sections of large mature To ascertain the presence of fungi, 10 trees. A sharp boundary separated intermedi• sticks (2 x 3 x 4mm) were cut from sections ate wood from heartwood, but a transition that had been taken from the sapwood periph- zone was not observed.

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Few ebony heartwoods of Diospyros were longitudinal streak varies between about 10- completely black or jet black. In most samples 18% within and between logs. In cross sec• thc heartwood comprised black alternating tions the streaks were mainly concentric with with brown to dark brown or dark grey streaks the paler portion having the most consistent with sharp boundaries. The heartwood periph• width but markedly variable in some parts. ery was always the blackest portion of the Diospyros marmorata (Anon. 1957), some black streaks and never brown of the alternat• specimens of D. celebica (Fig. 3) and D. pilo• ing streaks. Diospyros macassar (Anon., no santhera, for example, had marbled patterns date) and several D. celebica samples had of black and brown. The black streaks varied distinctively patterned streaks which were best in intensity with those in D. pilosanthera and seen when cut radially. The distance between D. rubra being much less intense than those streaks varied and was about 2-5 mm (cf. in D. mollis for example. 0.2-8 mm in D. ebenum; Wright 1904) al• A small (5 x 1.1 x 2 cm) specimen of D. though this may be more narrow near the tesselaria (Fig. 4) from Mauritius possessed pith. The proportion of black to brown in a an almost colourless 1.2 to 1.8 cm radially

Fig. 4. Diospyros tesselaria: Jet black heartwood, black radial protrusions of heartwood into colourless band, several isolated black vessels (arrows), brown, then black outer heartwood. - Fig. 5. Diospyros species from Uganda showing advance of ebony formation into living branch in the stern.

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Figs. 6-13. Diospyros tesselaria micrographs in reflected light.- 6: TS. Colourless band, black deposits absent in all cells, crystals in ray and axial parenchyma (arrows point to a few) (scale = 10 /lm). -7: TS. Border between colourless band and black heartwood (scale = 10 /lm). - 8: TS. Black protrusions into colourless band, black deposits in vcssels and surrounding fibrcs, with rays and parenchyma in colourless band empty or containing crystals (arrows point to a few) --7

Downloaded from Brill.com09/29/2021 08:35:13AM via free access Hillis & Soenardi P. - Ebony and streaked woods 431 wide band, containing 5 or 6 growth rings, sels (Fig. 15). A similar but less marked de• between the b1ack and outer dark brown re• velopment occurred at the heartwood periph• gions. It had the appearance of sapwood but ery when protrusions did not form (Fig. 16). none of the characteristic boundaries of in• Usually 1-3 lines of vessels in front of eluded sapwood. The change from the co10ur- the heartwood contained b1ack deposits (e.g. 1ess band at the inner boundary of the outer Fig. 4). Uncoloured tissues existed between brown heartwood region was more gradual, these vessels and the heartwood periphery the vessels were unchanged and did not con• (Figs. 10, 18). (In the case of D. philippinen• tain black deposits until inside the b1ack zone. sis sapwood, these black vesse1s existed in an erratic border of varying width surround• Microseopie description ing the heartwood.) The small (2-3 mm Starch grains were found in abundance in diameter) iso1ated b1ack spots occasionally the ray and axial parenchyma cells of sapwood seen in sapwood cross sections were often of different species but coloured deposits a single or a group of vessels and adjacent were absent. The intermediate wood of one tissues containing black deposits (e.g. D. sampie of D. celebica contained sm aller quan• pilosanthera). They can be of short 1ength and tities of starch than in the sapwood and sm aller isolated. quantities of dark deposits than in the paler Very small amounts of deposits appeared streaks of heartwood. In some ray cells starch in the vessels in sapwood. The vessels in the grains shared the lumen with crysta1s [report• paler streaks of D. celebica heartwood con• ed to be calcium oxalate (Griffioen 1934; Pur• tained linings or deposits of shiny, pale-brown kayastha 1982)]. Crystals were observed in material in small amounts (Fig. 14). Vessels the ray and axial parenchyma (e.g. D. tessel• in black streaks of heartwood contained abun• aria; Figs. 6, 8) and occasionally also in the dant to complete blockages of highly reflec• vessels of the pale coloured streaks of D. tive, black material (D. celebica Fig. 17 and celebica (Fig. 14) and D. mollis but were D. tesselaria Fig. 11) that were much greater often obliterated in the heartwood or black in amount than in the pale streaks. These de• streaks (Figs. 7, 15). The vessels, which posits were mainly responsible for the colour were of very small to sm all diameter, when of the black streaks in D. philippinensis and viewed on radial-longitudinal surfaces of D. papuana for example. sapwood appeared to be empty. In the pale streaks of several specimens Cross sections of D. moUis, D. tesselaria, [e. g. D. celebica (Figs. 14, 18), D. ferrea, D. pilosanthera, and D. sogeriensis had heart• D. lolin and D. mollis] the rays and paren• wood peripheries which sometimes showed chyma contained little if any dark deposits, (with x 10 lens) black, radial protrusions into although vessels frequently contained signifi• the sapwood (e. g. Fig. 4), or intermediate cant amounts 01' them. These black deposits wood. In the case of D. tesselaria the protru• were less dark in D. pilosanthera and in an sions consisted of 10-15 fibres surrounding unnamed species from Bomeo, and were avessei (Figs. 8, 9). None of the sapwood sometimes absent in the vessels 01' D. macas• tissues around the protrusions was coloured sar. The ray and axial parenchyma surround• (Fig. 8). The lumen of the fibres became pro• ing vessels at the border line between partly• gressively filled as the heartwood was ap• filled and filled fi bres contained few black proached (Figs. 8,9, 14) followed by the ves- deposits (Figs. 8, 9, 12, 13, 15, 16) and

(scale = 10 J.lm). - 9: TS. Enlargement of Fig. 8 (scale = 5 J.lm). - 10: RLS. Isolated vessels in colourless band containing black deposits and crystals; remainder of cells empty (sc ale =5 J.lm). - 11: TS. In heartwood elose to periphery; vessels, fibres full of black deposits, rays and paren• chyma empty or containing crystals (sc ale = 5 J.lm). - 12: TLS. Empty rays (scale = 10 J.lm). - 13: TLS. Empty rays, fibres with black deposits (sc ale = 5 J.lm).

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Figs. 14-19. Diospyros celebica micrographs in reflected light. - 14: TS. Brown streak, fibres and vessels partly filled with black deposits, rays and parenchyma containing crystals (arrows point to a few) but no black deposits (sc ale = 10 11m). - 15: TS. Brown streak (left) and com• pletely filled tissue 01' the black (right) streak (sc ale = 10 11m). - 16: TS. Vessel near border line of a brown and black streak showing decreasing lumens of fibres towards right hand side and rays lacking black deposits (sc ale = 5 11m). - 17: TLS. Partly filled vessel, black deposits absent in rays (scale = 5 11m). - 18: RLS. Vessels in brown streak containing black deposits and crys• tals, rays lacking in black deposits (scale = 10 11m). - 19: RLS. Cells filled with black deposits at the edge of black streaks (sc ale = 10 11m).

sometimes also further into the interior (Fig. The specimens of three Maba species show• 11). Usually they fiBed abruptly at the border ed aB the variations in heartwood appearance of black streaks (Fig. 19) when they lost their as found in Diospyros species. whitish appearance and became black and in• Examination at higher magnifications with distinguishable from the other tissues and the transmitted light confirmed the presence or deposits in them. absence ofblack deposits in various elements

Downloaded from Brill.com09/29/2021 08:35:13AM via free access Hillis & Soenardi P. - Ebony and streaked woods 433 as reported above. The vessels and fibres were the axial parenchyma and the majority of the filled with black deposits to varying degrees ray cells and accounted for the very sharply according to the intensity of the blackness of defined colour line between the intermediate the ebony. Fibre walls of boiled but unstained wood and the sapwood. The co1our of the sections from black regions in D. discolor, former becomes more brown on prolonged D. eben um and D. mollis as weIl as unnamed air drying. Occasiona1 patches of deposits species from New Guinea, Java, Malaysia appeared in the vessels in the intermediate and Gabon were brown. The unboiled and wood. Sampling difficulties prevented the unstained sections of black streaks of D. cele• detection of living cells in the intermediate bica had brown fibre walls. wood of our sampies of D. celebica although smaller arnounts of starch and a larger num• General characteristics ber of crystals were present in the rays com• The moisture content within each group of pared with the sapwood. We have found that 10 sampies of sapwood and 6 of intermediate in zones elose to the heartwood in different wood of tree C from Sulawesi were very simi• species, the deposits were in small amounts lar with means of 46.5% and 43.2% respec• of pale-brown, shiny material and were most tively. Notably the 10 heartwood sampies noticeable in the vessels. had a higher mean of 49.2% with the mean Intermediate wood is more common in D. of the innermost 5 sampies being 52.5%. celebica than is ebony, leading to the view it Of the many microtome sections of fresh is a formative stage for ebony. tangential surfaces, only those cut from the intermediate wood-heartwood boundary con• tained fungal hyphae. Similarly the only Streaks and their deposits sticks cultured in malt agar medium to be sur• As mentioned in Results most ebonies rounded by fungal hyphae after 1 week were contain jet black and paler streaks (Fig. 2). those from the intermediate wood-heartwood Brown gummy deposits have been observed, boundary in contrast to the other sticks which by other workers, in the rays and parenchy• were sterile. Two fungi were isolated and one ma of Diospyros heartwood whereas the ves• with a brownish appearance could not be sels and fibres were oceluded with black sub• identified in the absence of fruiting bodies. stances (Pearson & Brown 1932; Griffioen The other fungus was unmistakably a Fusa• 1934). Except with D. marmorata (Pearson & rium species. (The fungi/hyphae probably Brown 1932) it is not clear whether the did not result from contamination). The cores observations were made on black or pale from the West Java plantation trees were free streaks or both. The vessels in the paler re• from fungi and central heartwood. Centre• gions of D. marmorata frequently contained a decay was present in mature trees in Sulawesi yellow-brown 'gum', the rays and parenchy• and decay appeared to commence in the paler ma a brown black gum which partially filled streaks. the cells, the fibres were empty and crystals were numerous. The paler streaks appeared Discussion to contain more deposits than in the inter• mediate wood when present. However, as Intermediate wood with our studies, almost all the cells in the A pale brown 'intermediate wood' has black streaks were occluded by dark brown been observed in a few species and may oc• to black deposits as also in the black heart• cur in others as it is difficult to detect in dried wood of D. melanoxylon, D. oocarpa, D. sampies. Chattaway (1952) found living cells ebenum, and D. tomentosa (Wright 1904; and starch in the wide intermediate wood of Pearson & Brown 1932). a more than 50-year-old D. pentamera from Griffioen (1934) elaimed the composition which heartwood was absent. The amount of of the deposits in the rays and parenchyma starch was relatively less than in the sapwood. differed from those in the vessels and fibres Non-structural material appeared abruptly in of D. ferrea, D. celebica and 'Gaja merah'.

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He proposed the latter deposits arose from The longitudinal coloured streaks in some the high content of 'lignin' (determined by woods enhance their appeal for high-value 72% sulphuric acid) which partly disappear• uses, and do not affect strength but they have ed on heartwood formation to Ieave nearly recei ved little scientific attention. In addition co10urless cell walls. There is little evidence to streaked woods from Dalbergia and Dio• today that such a conversion can occur on spyros there are those from Microberlina braz• heartwood formation. Moreover polyphenols zavillensis, Brachystegia fleuryana, Dracon• (including quinones) become insoluble when tomelon spp., Atherosperma moschatum, heated with 72% sulphuric acid in the stan• Brosimum guianese, Spirostachys africanus, dard K1ason lignin determination and result Endiandra palmerstonii, Ocotea bullata, Pte• in high 'lignin' contents (Cohen 1936). rocarpus indicus, Araucaria hunsteinii etc. The dark-coloured, non-structural mate• Are the streaks in these woods a form of dis• rials present in black Diospyros heartwoods colouration which can end in decay or do are largely insoluble in organic and alkaline they exemplify adeviation from the formation solvents thus preventing determination of of heartwood extractives or non-structural amounts or composition in adjacent tissues, components? Ebony is a pronounced case of between trees or injured zones. Griffioen streaked wood found in other species and (1934) found the material in the parenchyma may provide an explanation for their for• was much more alkali soluble than that in the mation. vessels and fibres. Conclusions drawn from proximate chemical analyses (Griffioen 1933, The formation of heartwood and deposits 1934) indicate all these materials in 'tme Normally heartwood is formed by the ab• ebony' could be as high as 25 %. mptly enhanced metabolism at regular inter• In addition to sitosterol and triterpenes, vaIs of the living parenchyma cells in the the woods of Diospyros contain very small innermost layers of sapwood and subsequent• amounts of several naphthoquinones and ly extractives are released into the other tis• naphthols and their dimers (Herath et al. sues. In some Diospyros species there was 1978; Waterman 1986; Maiti & Musgrave little difference in black intensity between the 1986) and naphthaldehydes (Brown & Thom• darkest portions of the heartwood, regions son 1965) that are soluble in organic solvents. behind injured sapwood (Fig. 1), knots or The more stable and co10urless Macassar II isolated spots in the sapwood. Ebonised and III (dimethoxynaphthol and its methoxy wood often increases in volume around knots ether) have been isolated from different spe• (Fig. 3), in one case the black zone advanced cies and in yields of up to 1.9% (Lee et al. more than four growth rings into a living 1975) and 1.4% (Maiti & Musgrave 1986) branch within the stern (Fig. 5), of a species from D. celebica. These compounds are from Uganda, eventually these regions coa• thought to be the precursors of the more un• lesce with the heartwood. However, the com• stable yellow, red or green ortho- and para• mon occurrence of streaks of different black naphthoquinones, binaphthoquinones or intensities in ebony heartwood indicates their dis indigos and their derivatives extracted in formation follows a different mechanism much lower yields, possibly partly due to from that of normal heartwood extractives. their adherence to cellulosic materials in the Small black spots (c. 2 mm diameter) in cell wall. These compollnds are readily several sapwood cross sections were due to a oxidised enzymically to dark coloured ma• vessel or small groups of vessels and fibres terials and would become insoluble and im• with black contents. The origin of these spots mobile particularly when blocks are boiled could not be detected owing to the small size before sectioning. The naphthoquinones and of sampIe blocks. Black deposits in the larger their derivatives are charactel1stic of the Dio• spots (c. 5 mm) in the sapwood and inter• spyros genus and are found in different parts mediate wood of D. pentamera were found to of the trees. [Dalbergia spp. contain neotla• occlude in the first instance the lumens of the vanoids including the dalbergiquinones (Ses• vessels, then spread into the lumens of the hadri 1972; Donnelly et al. 1975.] fibres and then the cell walls (Chattaway

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1952). The adjacent living parenchyma and stillliving, would have access only to stored rays did not contain black deposits. In other starch in the intermediate wood or sapwood parts of these spots, fungal hyphae were seen (as in D. pilosanthera). We have found much in vessellumens and in their vicinity the ray more non-structural materials at the outer and parenchyma cells were dead and then edge than the interior edge of strcaks or pale filled with black deposits. In a similar situa• zones wherein the rays and sometimes the tion numerous thin (1 mm) black streaks are axial parenchyma surprisingly lacked or had seen on the transverse surface of Eucalyptus very small amounts of, coloured components marginata heartwood radiating outwards (by (Figs. 2, 6). Also the axial parenchyma and up to 5 cm) to the sapwood and commencing particularly the rays for about 5 mm into the and finishing abruptly. These 'pencilled' darkest outer heartwood lacked black depos• areas in roots, sterns and branches may be its. The origin of the deposits in the vessels axially quite extensive. Fistulina hepatica has and fibres could not be ascertained. been isolated from these areas in sapwood and In some logs from . very old trees (c. 0.5 m outer heartwood and the dark colour is due to diarn.) about one-half of the ebony heartwood excessive infiltration of the fibre and vessel boundary can extend to the cambial region lumina with abnormally heavy dark deposits leaving a narrow sapwood in the rest of the (Tamblyn 1937). cross section. This behaviour is indicative of Longitudinal sections of several Diospyros fungal influence. Nothofagus cunninghamii species showed vessels containing black de• provides a similar example of this behaviour posits about 1 mm in front of, and isolated and fungal hyphae have been found in the from, the heartwood periphery (Fig. 4). In darker heartwood and the dark axial streaks other cases black projections from the heart• in radially irregular patterns (Chattaway 1952; wood periphery were very largely due to de• Hillis 1987). In this case the fungus Chalara posits in vessels and fibres, which was very australis is probably conveyed by the wood noticeable in D. tesselaria (Figs. 4, 8, 9). Have beetle Platypus subgranosus (Kile & Hall these deposits been initiated by microbiologi• 1988). cal activity as in Eucalyptus marginata and are they associated with the presence of wet• Formation of ebony wood? We propose ebony formation in appropri• We have isolated from the region of the ate Diospyros species is initiated by stern or intermediate wood and the adjacent black branch injury with irregularly shaped zones heartwood of D. celebica, but not elsewhere, or by root in jury and associations with the a Fusarium sp. fungus as well as an unidenti• relatively uniform or streaked heartwoods. fied one. Accordingly a possible hypothesis Absence of ebony in some trees of the same is that ebony formation is a response to fun• species, either in the same locality or when gal or other microbiological activity. The eb• grown in a different habitat, could be due to onised inner wood of Tree C was found to the absence of invasion of appropriate fungi be wetter than the surrounding intermediate or microorganisms. wood. From the evidence above the hyphae The black axial streaks in the sterns of D. could move axially through the vessels in the celebica can partly or completely encirc1e the inner intermediate wood or sapwood. How• stern in roughly concentric circles. The rela• ever, the larger production of deposits in all tively regular patterns ofaxial streaks that are tissues of black streaks would require increas• seen when the stern is cut radially meander ed activity of living ray and axial parenchyma. slightly from the axial direction (Fig. 2). The influence of the fungi could also move Such patterns could be due to a sm all group laterally. In that case the largest amount of of fungal hyphae periodically (or perhaps extractives would be expected to be at the several separated groups) entering the roots abrupt heartwood periphery, or outer edge of and then the vessels of the inner sapwood black streaks, which had available stored and (or intermediate wood) of the stern to oxidise translocated carbohydrate. The ray and pa• firstly their contents to black deposits and renchyma on the inner side of the streaks, if then stimulate production of non-structural

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material. The formation of large blister type cell walls of D. celebiea and 'Gaja merah' streaks (Fig. 3) are unusual and may be the were not coloured although the walls of the result of invasions of widely spaced groups particularly black heartwood of D. ferrea of fungal hyphae perhaps from different were yellow. It is not clear whether black or roots. pale streaks of the first two species were ex• amined. We have found the fibre cell walls in Diseolouration the black streaks of our sam pie of D. eelebiea Discolouration can be due to three possible were brown as they were also in unstained causes (Shigo & Hillis 1973; Bauch 1984), but previously boiled sections of D. eelebiea, namely environmentally initiated physiologi• D. mollis as weil as unnamed species from cal processes, biochemical processes, and Papua New Guinea, Java and Gabon. Wright chemical reactions. The last cause is unlikely (1904) also reported the cell walls in D. me• in the present situation. Discoloured wood is lanoxylon became discoloured on heartwood often more sharply defined than bands in formation as they sometimes did in D. oocar• heartwood and is caused by environmentally pa. The presence of coloured cell walls, and initiated physiological processes. It is usually the consistent and concentric dark-pale longi• a zone of several millimetres around an injury tudinal streaks characteristic of ebony are not to the sapwood or infected branch stubs; it usual for a discoloured wood. can be associated with wetwood and extends It remains to be proven whether the streaks axially for so me distance (Shigo & Larson in ebony or other woods are different stages 1969; Bauch et al. 1982). The chemical com• of discoloured wood or represent different position is different from that of heartwood, types of conversion to heartwood. Although the extractives may offer some degree of pro• occurring on a sm aller and localised scale, tection, and melanistic substances form in there are several examples of pulsating or some species (e.g. Hart 1968). Discoloured alternating formation of specific organic crys• wood yields a larger amount of ash and con• tals or extractives taking place within a few tains more moisture than the surrounding tis• cells (Hillis 1977, 1987). These presurnably sues (Shigo & Hillis 1973; Bauch et al. 1982). occur by genetically controlled biochemical This is the case with D. tomentosa which has processes. yielded a high amount of ash of 2.34% (oven dry basis) consisting mainly of calcium car• bonate (1.79%) and magnesium carbonate Acknowledgement (0.29%) (Gamble 1922). Griffioen (1933, We are grateful to Dr. G. Downes for his 1934) obtained 0.57% ash (dry basis) from a excellent reflection micrographs of polished Diospyros species heartwood. However the sections and discussions, Mr. J. llic for dis• proportions of brown and black streaks in the cussions, Mr. N. Walters for identification of sampies were not stated. The moisture con• fungi and Dr. Pong Sono of Thailand for a tent ofthe heartwood (49.2% and 52.5%) of D. mollis sampie. our D. eelebica specimen was also higher Part of this work was done in the Depart• than surrounding tissues (intermediate zone ment of Forestry, Australian National Uni• 43.2%, sapwood 46.5%). Wetwood, which versity, Canberra in partial fulfilment of a probably contains bacteria, can have much PhD degree (S.P.). higher amounts of poly phenols than the sap• wood or heartwood (cf. Bauch et al. 1975). Indications are that an environmental process References is involved when plantation trees of D. cele• Anonymus (no date). Wood specimens: 100 biea in Java lacked ebony and younger trees reproductions in colour. P.M. Nairn (ed.), in the natural habitat of Sulawesi contained 206 pp. Nema Press, London. ebony. Anonymus (1957). Wood specimens: 100 re• Discoloured wood usually lacks extractives productions in colour. Second collection in the cell wall and this is an uncertain feature (P.M. Nairn, ed.), 205 pp. Tothill Press, with Diospyros. Griffioen (1934) found the London.

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Bauch, J. 1984. Discolouration in the wood Kile, G.A. & M.F. Hall. 1988. Assessment of living and cut trees. IAW A Bull. n. s. of Platypus subgranosus as a vector of 5: 92-98. Chalara australis, causal agent of a vascu• Bauch, J. , W. Höll & R. Endeward. 1975. lar disease of Nothofagus cunninghamii. Some aspects of wetwood formation in New Zealand J. For. Sei. 18: 166-186. fir. Holzforschung 29: 198-205. Lee, e.L., Y. Hirose & T. Nakatsuka. 1975. Bauch, J., G. Seehan & R. Endeward. 1982. The inhibitory effects of Diospyros sp. Characterization of sapwood and brown heartwood extractives on the curing of un• heart in Terminalia superba. Holzfor• saturated polyester resin. Mukuzai Gakka• schung 36: 257-263. ishi 21: 107-112. Brown, A.G. & R.H. Thomson. 1965. Eb• Mabberley, D. J. 1989. The -book. ony extractives, Part II. J. Chem. Soc. Cambridge Univ. Press. 4292-4295. Maiti, B.e. & O.e. Musgrave. 1986. Ebena• Burkill, I.H. 1935. A dictionary of the eco• ceae extractives. Part 9. New naphthoqui• nomic products of the Malay Peninsula. nones and binaphthylquinones from Ma• Vol. 1: 825-834. London. cassar ebony. J. Chem. Soc. Perkin Trans. Chattaway, M.M. 1952. The sapwood-heart• 1: 675-681 and references cited therein. wood transition. Australian Forestry 16: Metcalfe, e. & L. Chalk. 1950. Anatomy of 25-34. the dicotyledons, Vol. II: 800-806. Per• Cohen, W.E. 1936. The chemistry of Aus• gamon Press, Oxford. trahan timbers, Part 5. A study of the lig• Pearson, R. S. & H. P. Brown. 1932. Com• nin determination. Pamphlet No. 62. CSIR mercial timbers ofIndia, Vol. 2: 682-708. Commonwealth 01' Australia. Purkayastha, S. K. 1982. Indian woods, Vol. Donnelly, D. M. X., J. O'Reilly & W. B. 4: 122-131. Whalley. 1975. NeoHavanoids of Dalber• Seshadri, T.R. 1972. The polyphenols of gia melanoxylon. Phytochem. 24: 2287- Pterocarpus and Dalbergia woods. Phyto• 2290. ehern. 11: 881-898. Gamble, J.S. 1922. A manual ofIndian tim• Shigo, A.L. & W.E. Hillis. 1973. Heartwood, bers. Ed. 2a. Sampson Low, Marston & discolored wood and microorganisms in Co., London. living trees. Ann. Review Phytopathology Griffioen, K. 1933. A study of the dark col• 11: 197-222. oured duramen 01' ebony. Proc. Kon. Ned. Shigo, A.L. & E.vH. Larson. 1969. A photo Akad. Wetensch. 36: 897-898. guide to the patterns of discoloration and Griffioen, K. 1934. A study of the dark col• decay in living northern hardwood trees. oured duramen of ebony. Rec. Trav. Bot. USDA For. Servo Res. Paper NE-127. Neerl. 31: 780-809. Sidiyasa, K. 1989. Some aspects of the ecol• Hart, J.H. 1968. Morphological and chemical ogy of Diospyros celebica at Sausu and in differences between sapwood, discolour• Central Sulawesi. Buletin Penelitian Hutan ed wood and heartwood in black locust and (No. 508): 15-26. Osage orange. Forest Sei. 14: 334-338. Surianegara, T. 1967. Some information on Herath, W.H.M.W., N.D.S. Rajasekera, the Indonesian ebony tree species. Com• M. U.S. Sultanbawa, G. P. Wannigama & munication No. 92. For. Res. Inst. Bogor. S. Balasubramaniam. 1978. Triterpenoid, Tamblyn, N. 1937. Decay in timber with spe• coumarin and quinone constituents of elev• cial reference to jarrah (Eucalyptus margi• en Diospyros species (Ebenaceae). Phyto• nata). Australian Forestry 2: 6-13. chern. 17: 1007-1009. Waterman, P.G. 1986. A phytochemist in the Hillis, W. E. 1977. Secondary changes in African rainforest. Phytochem. 25: 3-17 wood. In: F.A. Loewus & V.e. Runeek• and references cited therein. les (eds.), Recent advances in phytochem• Wright, H. 1904. The genus Diospyros in istry 11 : 247-309. Ceylon: its anatomy and taxonomy. Ann. Hillis, W.E. 1987. Heartwood and tree exu• Roy. Bot. Gard., Peradeniya 2 (ii): 133- dates. Springer Verlag, Berlin. 268 pp. 210.

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