IAWA Bulletin n.s., Vol. 9 (1), 1988: 75-87
WOOD FLUORESCENCE OF INDIGENOUS SOUTH AFRICAN TREES
by
Stephanie T. Dyer South African Forestry Research Institute, P.O. Box 727, Pretoria, 0001, South Africa
Summary The fluorescence characteristics of South study of growth rings, the detection of ligni African hardwoods and their extracts were fication and the identification of diseased studied to determine their value in wood iden wood (Vodrazka 1929; Radley & Grant tification. Heartwood specimens and water 1948). Vodrazka (l.c.) remarked on the use and ethanol extracts of a1together 179 species fulness of wood fluorescence in rnacro- and representing 108 genera and 46 farnilies were microscopic studies using three examples, exarnined in longwave ultraviolet light. Ad Robinia pseudoacacia, Ailanthus glandulosa ditional tests were conducted for the presence and Rhus typhina. He studied heartwood of Aluminium natural saponins. The findings fluorescence in addition to fluorescence in of this research correspond with the current water, a1cohol and acetone extracts. An addi knowledge on wood fluorescence. The fami tional 40 wood species are listed by him as lies Leguminosae, Rutaceae and Anacardia being fluorescent. These include the genera ceae showed positive fluorescence for the Rhus, Acacia, Swartzia and Erythrophlewn. majority of their species. Platylophus trifolia Miller and Baas (1981) incorporated the fluo tus is the only indigenous species with a pos rescence of heartwood and its extracts in the itive reaction to the test for Aluminium. The IAWA 'Standard list of characters suitable froth test for natural saponins in wood has for computerized hardwood identification. ' variable results, restricting its significance in The aim of this study, which was initiated wood identification. These results show that in 1985, was to assess the presence of UV fluorescence is a useful characteristic in wood fluorescence in South African woods with the identification and may be applied as a rapid view to using the results for separating close and easy test to verify certain identifications. ly related species should they show differen Key words: Heartwood fluorescence, wood ces in fluorescence. The results obtained will identification, longwave ultraviolet light, be compared with existing data on wood flu Aluminium, froth test, saponins, South orescence and then be added to the list of African hardwoods, extract colours. characters used in the identification of hard wood species. Introdudion The incorporation of the results into a The use of ultraviolet light to study the local and possibly international data base is fluorescence characteristics of wood was envisaged. started many years aga when Goppelsröder studied the fluorescence of extracts of Java Materials and Methods nese woods in 1867 (Vodrazka 1929). The wood specimens tested are represen Longwave ultraviolet radiation has a range tative of the collection of indigenous timbers from 260 to 400 nm, and the best wave1ength of the South African Forestry Research Insti for the study of wood fluorescence is approx tute. Altogether 852 specimens representing imately 365 nm (Panshin & De Zeeuw 1980). 108 genera and 179 species were tested. Wood fluorescence has been used for a wide Where possible, five or more replicates of range of applications. These include the dis each species were tested, but in a number of tinction of sapwood from heartwood, the cases only a single specimen was available.
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All tests were carried out according to the ed for approximately one minute, and the ex methods prescribed by Miller (1981), with tract colour scored as colourless, red, brown, minor modifications. In the recording of the yellow, reddish-brown, yellowish-brown or results, the recommendations of Miller were none of these as in Miller (1981). Some dif followed (Table 1). If 0 to 20% of the sam ferences in opinion occurred when extract pIes tested were positive, the taxon was re colours were recorded and a second opinion corded as being negative. If21 to 80% ofthe had to be considered in some cases. A possi sampIes were positive, the taxon was record ble solution to these problems would be the ed as variable and if 81 to 100% of the sam use of a standardised colour chart. It was also pIes tested positive, the taxon was recorded noted that the colour faded in time and it was as positive. therefore important to record this immedi Heartwood fluorescence was determined ately after heating. by removing a strip approximately 5 mm thick from the end surface of each specimen Ethanol extract fluorescence with a saw and studying the freshly exposed The method for this test was similar to surface under longwave UV light. The spec that for water extract fluorescence, except imens were recorded as either fluorescent that 95% ethanol was used instead of water. (colour given) or not fluorescent (-). Only The scoring was the same as for the test for sampIes which exhibited adefinite yellow, water extract fluorescence. green, purple, orange or blue fluorescence were recorded as being fluorescent. Dull blue Ethanol extract c%ur and dull green reactions were scored not The same method as that for water extract fluorescent, as these reactions may be due to colour was used. reflections of the UV light. Chrome Azurol-S test/or Aluminium Froth test to determine the presence 0/ na A 0.5% solution of chrome azurol-s was tural saponins prepared in sodium acetate and distilled wa Approximately 2.5 ml of sawdust was re ter. Two drops of reagent were applied to the moved from each sampie, placed in a vial freshly exposed end grain of each sampie. and covered with 10 ml of distilled water, Positive reactions developed a bright blue buffered at a pH of 6.8, shaken vigorously colour in a matter of minutes. for 10 to 15 seconds, and immediately view ed under UV light to score for water extract Results and Discussion fluorescence. One minute after shaking, the The shortage of relevant literature on wood froth (if present) formed by the water extract fluorescence made initial interpretation of was scored as folIows: Positive (+) if froth the results of the South African hardwoods was still present and covered the surface of difficult. Fortunately the Forest Products Lab the solution, negative (-) if all froth had oratory of the United States Department of disappeared, and variable (V) if froth was Agriculture was prepared to compare these present, but only around the edge of the test results with the results of the corresponding tube and did not cover the entire surface. genera in their collection. The results listed below have been found to compare favour Water extract fluorescence ably with existing results. Immediately after shaking the extract for the froth test, the solution was examined un Heartwood fluorescence der UV light. Extracts which fluoresce ex Of the 46 families tested for heartwood hibit definite blue, green, yellow and purple fluorescence. 10 were positive in that some colours. Some extracts showed positive fluo orall the genera fluoresced. The fluorescence rescence but the colours were weaker. colours were yellow, green, yellowish-green, blue, and orange and the colours varied in Water extract colour intensity. Most heartwoods fluoresced with a After the froth test, the extracts were boil- yellow or yellowish-green colour.
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Table 1. Fluorescence characteristics of indigenous South African hardwoods . ., "Cl 8 l'l ., I:i ., u ., [;l ~ I:i .€ ., ... 1 ., [;l .u a> .s 0 Ul > Ul [;l :t;ä ~ § ., ., ., os ~ 0 " .s'~ p...... :: "8 ~ 0 ~'': ..:: .., utbD 'Gl os ..," "8 .., u ~ ..:: u ]~ Ul " 8.~ ~ "Cl .. I ~ ..,~ . '5 0 ~ ., "~~ Ul ., ~., ~ ., 1 ... '0 '0 ., ., ..,~ .s~ ...... I:i 1! tä os § .~ -:5 os .s .s .~ Species s lil., o bD -:5 -:5 ;: z" ~ ~ ~ ~ ~ r.< r.< 0& Anacardiaceae Harpephyllum caffrum 5 V brown yellowish- brown Sclerocarya birrea 8 V yellowish- yellowish- brown brown Protorhus longifolia 4 green + brown bright green brown Rhus chirindensis 8 green + reddish- red brown Rhu8 gueinzii 4 green + reddish- green red brown Rhus lancea 7 green + reddish- green red brown Apocynaceae Gonioma kamassi 8 green bluish- yellow bright yellow green yellowish- green Rauvolfia caffra 5 V brown yellowish- brown Aquifoliaoeae Ilex mitis 8 + yellowish- yellow brown Araliaceae Cussonia .picata 8 + yellowish- colourless brown Schefflera umbellifera 3 ligh blue lightblue colourless light blue colourless Asteraoeae Brachylaena discolor 6 V yellow light blue yellow ssp. discolor Brachylaena discolar 3 V yellow light blue yellow ssp. transvaalensis Brachylaena glabra 1 yellow light blue yellow
Brachylaena huillensis 4 V yellow blue reddish- brown Tarchonanthus galpinii 2 V yellowish- yellowish- brown brown Balanitaceae Balanites maughamii 2 + yellow bright blue yellow
Bignoniaceae Kigelia africana 2 V yellowish- yellowish- brown brown Bombacaceae Adansonia digitata 2 + yellow grey
Boraginaceae Cordia caffra 5 + reddish- bright brown brown purpIe
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(Table 1 continued) 0> 0> u u <: 0> <: 0> ""21 0> 1Jl .. .~>' ]: ~ 0> ... 21 0> 1Jl ... .u 4) 1Jl +r! ::s § 6 .. :> 0> 0> ';'~ 0 .s:;:l '" ... ::s~ <;:: "8 'a 0 ~ .~ <;:: '0 ..., Clfg\, ::s ·S :> ..., ..., u ~ <;:: u u" ] ~ 8.~ os ::s • ...... I '"0 0 ...,~ b ~ >I ., ~~ ... "" '" 0> ~0> I 0> .. ...,~ ., '0 '0 .8 .s~ ...... <: § 8 ~ ,fi os .s .s os Species ::s 0> os os ,fi ,fi li z ::z: &~ ~ ~ r.1 r.1 08- Burseraceae Commiphoro horveyi 4 yellow colourless Commiphoro lugardae 6 yellow colourless Buxaceae Buxus macowanii 5 colourless colourless Capparaceae B08Cia albitrunca 2 colourless yellow colourless Celastraceae Cassine crocea 5 + reddlsh- yellowish- brown brown Cassine burkeana 1 V yellow yellowish- brown Cassine eucleiformis + reddlsh- yellowish- brown brown Cassine peragua 4 + reddlsh- red brown (light) Catlza edulis 3 + red reddlsh brown Maytenu8 acuminata 2 V reddlsh· yellowish- brown brown Maytenus peduncularis 5 V yellowish- colourless brown Pleurostylia capensis 5 + orange yellowish brown Pterocelastrus 5 + red red tricuspidatus Combret&ceae Combretum apiculatum 5 + brown purpIe brown Combretum collinum 1 + reddlsh- yeIIowish- brown brown Combretum 5 + yellow yellow erythrophyllum Combretum hereroense 2 + yellowish- red brown (orange) Combretum imberbe 8 + red brown Combretum krauss;; 7 + yellow purpIe yellow Combretum zeyheri 3 + yellowish- yellow brown Terminalia sericea 8 + yellow yellow
Comaceae Curtisia dentata 8 + reddlsh- reddish· brown brown Cunoniaceae Cunonia capensis 6 V red reddish- brown Platylophus trifoliatus 8 V yellowish- yellowish- + brown brown Ebenaceae Diospyros dichrophylla 4 V yellow yellow
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(Table 1 continued)
Diospyros whyteana 8 + yellow yellow Euclea crispa 2 V brown yellowish- brown Euphorbiaceae Androstachys johnsonii 5 V colourless yellowish- (milky) brown Bridelia micrantha 6 V yellowish- yellowish- brown brown Croton gratissimus 2 V colourless colourless Croton megalobotrys 2 + yellow colourless Croton sylvaticus 7 V colourless colourless Drypetes gerrardii 4 + yellow colourless Heywoodia lucens 8 + yellow yellow Lachnostylis hirta 3 + reddish- red brown Macaranga capensis 7 V brown yellow Spirostachys africana 8 yellowish- brown brown Flacourtiaceae Homalium rufescens 1 V blue colourless blue colourless Kiggelaria africana 5 + green red yellowish- yellowish- green brown Scolopia mundii 4 + yellowish- orange brown Hamamelidaceae Trichocladus ellipticus 1 V brown reddish- brown Icacinaceae Apodytes dimidiata 3 + yellowish- brown brown Lauraceae Cryptocarya liebertiana 5 V colourless colourless Cryptocarya myrtifolia 2 V yellow coIourIess Ocotea bullata 5 blue yellowish- bIue yellowish- brown brown Ocotea kenyensis 4 coIourless blue coIourIess
Leguminosae (Caesalpinoideae) Afzelia quanzensis 9 V reddish- green reddish- brown brown Baikiaea plurijuga 9 + red green red Burkea africana 8 yellowish- + reddish- light bIue red green brown Colophospermum mopane 8 green + green red green red Cordy/a a{ricana 6 V bIue yellowish- green yellow brown
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CI) (Table 1 continued) 0 I::l "CI 8 CI) CI) I::l CI) 1il ~ .~> CI) :1 1:l ~CI) 1il .s CI) ~ ~ § ~ .~ ..CI) 1il .s ~~ ~ ~ 0;:: 'a ~ .~'!: :0 "8 rlfbD 'a 0 0;:: "8 .... :0 .S os ...... ] ~ ~ 0;:: " j .. "CI ..8.~ I i!'-:: '5 0 .... ~ ~ ~ os~ .. CI) i ~CI) CI) CI) ... ~ .s > ~ '0 g .8 ~ 1ä os § .~ Species e ~ ß 1: .~ :0 CI) ~~ 1l 1l z :t: .t~ ~ ~ ~ ~ o&. (Legum.·Caes. continued) Erythrophkum africanum 5 green + reddish· green red hrown Guibourtia arnoldiana 2 V green yellow light blue yellowish- brown Guibourtia coleosperma 5 green V reddish- purpIe red hrown Guibourtia soussae 4 green V reddish- green reddish- brown brown Peltophorum africanum 5 V reddish- lightblue red brown Schotia brachypetala 8 V reddish- bright blue red brown Swartzia madagascariensis 7 yellow bright blue red Umtiza listerana 1 bright V yellowish- red yellowish- reddish- Leguminosae yellow green green brown Downloaded from Brill.com09/23/2021 12:06:09PM via free access Dyer - Fluorescence of South African woods 81 CI) (Table 1 continued) 1! 8 CI) CI) ~ '" u ;; CI) 1J! ~ ~ .~ CI) ... .,1 CI) 1J! .., CI) .s +,! CI) ... 1J! ::> g 5 '" ;- CI) ';'~ s 0 .B~ '" ::> r;::: '8 rt:J oS 'a ~.~ r;::: '0u .., ·Iil ;- .., .., tl ...!.~ § ~ g ~ r;::: &--" a! ~ ::> • .. [ '" ..,~ '5 '"0 ~x ~ ~ i ~~ ... ~ .s'" ;-CI) CI) CI) '0 CI) CI) Jl .., . ,.c: :Q ...... § Species ~ .s 1 CI) oS .;i .;i J~ ~ l!: ~~ ~ ~ 0& (Legum.-Mim. continued) "" "" Acacia nigrescens 8 yellowish- + yellowish- yellowish- reddish- green brown green brown Acacia robusta 5 + reddish- yellowish- reddish- brown green brown Acacia sieberana (sapwood) 6 V colourless blue colourless yeUmria tortilis l! yellow blue colourless ssp. heteracantha Acacia xanthophloea 4 yellowish- V yellowish- blue colourless green brown Dichrostachys cinerea 2 V yellowish- blue reddish- brown brown Loganiaceae Anthocleista grandiflora 7 V yellow yellow Buddleja salviifolia 1 yellow yellowish- brown Nuxia congesta 2 V colourless colourless Nuxia floribunda 8 V brown yellowish. brown Strychnos cocculoitks 1 colourless colourless Strychnos tkcussata 5 yellow bright yellow bright blue yellow specks light blue (milky) (bright) inc1.phloem Strychnos henningsii 3 V brown yellowish- brown Strychnos 1 V brown colourless madagascariensis Strychnos mitis 4 yellowish- yellowish- brown brown Strychnos pungens 2 V yellow yellow Strychnos spinosa 4 yellow yellow Meliaceae Ekebergia capensis 8 + yellowish- yellow brown Entandrophragma 4 + reddish- red caudatum brown Entandrophragma + reddish- red spicatum brown Trichilia emetica 7 + yellowish- yellow brown Monimiaceae Xymalos monospora 5 yelJow yellowish- yellow yelJow green Moraceae Ficus burkei 4 + yellowish- colourless brown Ficus capensis 5 V yellow/ colourless yellowish- brown Downloaded from Brill.com09/23/2021 12:06:09PM via free access 82 IAWA Bulletin n.s., Vol. 9 (1),1988 (Table 1 continued) '" '"d fl il $ c:: (,) ;;- '"al '" "~ J c:: ~ al .. $'" .. '" .. ::s .u ~ 1Il ~ g'" 0 '" > '" ~~ ~ 0 '0 $:0 '" r;:: (,) 15. ,G ::s '0 u:J CI! '" 8'" .~ r;:: (,) +' +' ,bI) ::s 'Iil > +' +' § (,) (,) r;:: 8..-:: ~::s ~• .. '"d .. I 'ö 0 +' ~ ! ! 0 ~ ~ ~~ .. ~ $,G'" '" '0'" '" jl +' ..'" ..'" c:: §'" .~'" oS CI! $ $ CI! 1il o bI) 1 .. -~ Species § oS oS ..c:: ~ z ::r:'" ~ ~ ~ ~ t: Rhamnaceae Berchemia discolor 7 green V red green yellowish- brown Downloaded from Brill.com09/23/2021 12:06:09PM via free access Dyer - Fluorescence of South African woods 83 ., (Table 1 continued) "Cl 8 1:! ., I'i ., 21 <.I ~ ., 111 !IJ .~ ., J 21 I'i +.! &l ... g !IJ g ~ ~ ., '"&l "Q;'~ ~ g '0 21 ,~ "a '0 0;::: <.I Cf.l~ '"~ ,~ '~ 0;::: <.I ...... '!il > " § 0;::: ...... ]~ !IJ " &--:: "Cl .. I " . "S 0 ... ~ ~ ~ ~~ ~ !IJ '" I I '0 ] ... 21 ,~ ...'" ...'" § S'" ,~ '" lii 21 1 ] ,<;:: Species § ~~ ..s ..s z :z::'" ~ ~ ~ ~ r Downloaded from Brill.com09/23/2021 12:06:09PM via free access 84 IAWA Bulletin n.s., Vol. 9 (1),1988 Table 2. Species which exhibit an exceptionally bright fluorescence in heartwood. Albizia adianthifolia Mimosaceae yellowish-green Acacia galpinii Mimosaceae yellow Umtiza Iisterana Caesalpiniaceae yellow Xanthocercis zambesiaca Fabaceae yellow Table 2 Iists the species which exhibit an Aquifoliaceae tested) and some species of exceptionally bright fluorescence. the Sapotaceae. The water extracts of these The majority of the genera tested of the specimens produced large amounts of froth Caesalpiniaceae, Mimosaceae, Rutaceae, Ana when shaken. Other families, of which the cardiaceae and Rharnnaceae were positive majority or all of the genera tested positive, for this test. are the Mimosaceae, Fabaceae,Meliaceae, The results correspond with those of Mil Anacardiaceae, Celastraceae, Rhamnaceae, ler (1981) who noted that the heartwood of Flacourtiaceae, Combretaceae, Myrtaceae, species of the Leguminosae (Mimosaceae, Comaceae, Boraginaceae, Oliniaceae, Bala Caesalpiniaceae and Fabaceae) and Anacar nitaceae, Icacinaceae, Rhizophoraceae, and diaceae fluoresce. Myrsinaceae. The latter seven families are Other genera that proved to have fluores represented by only one or two species. cent heartwood are listed in Table 1. Only four of the 13 species of the Caesal Heartwood fluorescence is a rapid test that piniaceae tested were positive, eight were can be very useful in macroscopic identifica variable and one was negative. tion of wood or in verifying a microscopic Generally the speeimens tested produced identification. In this regard an interesting more froth than those tested by the Forest case study can be mentioned: Berchemia zey Products Laboratory (USDA). A possible ex heri (Rharnnaceae), locally called red or pink planation for this phenomenon could be the ivory, is a very popular species for wooden size of the partieles used to prepare the ex jewellery and knife-making because of the tracts. In contrast to the much larger shavings beautiful red or pinkish colour of the heart used by other researchers, sawdust was used wood. Berchemia discolor, brown ivory, has here and when shaken it usually produces an almost identical anatomical structure to some froth, which is not always the case with that of red ivory, but it has a reddish-brown the larger shavings. The fine particles also colour. Without botanical material it is often allow better extraction and the extraction col impossible to separate the two speeies as B. ours were influenced by this. zeyheri heartwood can fade to the colour of B. discolor when exposed to sunlight for a Water extract f!WJrescence long period. When sampies of heartwood of Water extract fluorescence was encoun the two species are placed in ultraviolet light, tered more frequently than heartwood fluo separation is easy. Berchemia zeyheri has a rescence (13 families have positive-testing characteristic orange fluorescence, while B. speeies) but the colour reactions were not as discolor fluoresces with a green colour. This variable. Colours noted were blue, green, distinction was applied recently for the posi yellowish-green and bluish-green. Five spe tive identification of a consignment of 14 eies exhibited a brilliant water extract fluo tons of brown ivory that was supplied incor rescence (Table 3). rect1y to a timber merchant as red ivory. In only 3 farnilies, Rutaceae, Ptaeroxyl aceae and Monimiaceae, the water extracts of Froth test all the species tested fluoresced but the last In the test for natural saponins in wood, two families are represented by only one spe the most intense reactions were found with cies each.Other families which tested positive, Ilex mitis (the only species of the family but from limited sampIes appear in Table 1. Downloaded from Brill.com09/23/2021 12:06:09PM via free access Dyer - Fluorescence of South African woods 85 Table 3. Species which exhibit a brilliant water extract fluorescence. Xanthocercis zambesiaca Fabaceae yellowish-green Ptaeroxylon obliquum Ptaeroxylaceae blue Olea europaea subsp. qfricana Oleaceae blue Strychnos decussata Loganiaceae blue Breonadia salicina Rubiaceae blue Table 4. Species with exceptionally bright ethanol extract fluorescence. Acacia erioloba Mimosaceae yellowish-green Schotia brachypetala Caesalpiniaceae blue Swartzia madagascariensis Caesalpiniaceae blue Millettia stuhlmannii Fabaceae green Virgilia oroboides Fabaceae blue Xanthocercis zambesiaca Fabaceae yellow Balanites maughamii Balanitaceae blue Ptaeroxylon obliquum Ptaeroxylaceae blue Protorhus longifolia Anacardiaceae green Strychnos decussata Loganiaceae blue Gonioma kamassi Apocynaceae yellowish-green Cordia cajfra Boraginaceae purple Contrary to the findings of Miller (1981) wood but it has a colourless, rnilky water who found that all species of the Anacardia extract. Sclerocarya caffra is a light reddish ceae and Loganiaceae tested scored positive brown wood with a yellowish-brown ex for this test, the South African representatives tract. of these families generally did not follow The taxa with a distinct red extract are Cu this trend. Strychnos decussata (Logani nonia capensis (Cunoniaceae), Colophosper aceae) was the only positive scoring species. mum mopane andBaikiaea plurijuga (Caesal piniaceae), Catha edulis and Pterocelastrus Water extract colour tricuspidatus (Celastraceae), Berchemia dis The results produced by this test were sim color andB. zeyheri (Rharnnaceae),Kiggela ilar to those by Miller (1981). Dark coloured ria africana (Flacourtiaceae), Combretum woods had brown, yellowish-brown and red imberbe (Combretaceae) and Mimusops caf dish-brown extracts, and light coloured fra (Sapotaceae). All these, excepting Com woods produced colourless or yellow ex bretum imberbe, have reddish heartwoods, tracts. However, there are a few interesting and one would therefore expect a red water exceptions, which are important for identifi extract. However, in the case of C. imberbe cation: the colour of the heartwood is greyish-black Ocotea bullata and O. kenyensis (Laura to black and a red water extract is therefore ceae) both have brown wood but produce an important character for the identification distinct yellow extract, which are unexpected of C. imberbe wood. characters for these woods. Swartzia mada Species which have a distinct orange col gascariensis (Caesalpiniaceae) is a dark red oured water extract are Pleurostylia capensis dish-brown wood, but has a yellow water (Celastraceae), Ochna arborea, O. pulchra extract which is useful in identification. An (Ochnaceae), Mimusops obovata and M. zey drostachys johnsonii is a yellowish-brown heri (Sapotaceae). Downloaded from Brill.com09/23/2021 12:06:09PM via free access 86 IAWA Bulletin n.s., Vol. 9 (1),1988 It is clear from the results that the colour woods tested, were similar or slightly darker of the water extract is more useful in veri or lighter than the colours of the water ex fying an identification, than in the identifica tracts. There were, however, a number of tion process itself. species of which the colour of the ethanol extract was completely different to that of Ethanol extract fluorescence the water extract (Table 5), and this could be This test had more interesting and colour useful in identification. ful reactions than both the heartwood and It must be emphasised that colour is a water extract tests. Of the 46 farnilies tested subjective character and it is suggested that 22 have positive testing species. The fluores some form of standardisation of this be used cence colours were blue, green, purple, yel in future studies. low, yellowish-green, green, orange, and bluish-green. The most significant results are Chrome Azuro/-S test listed in Table 4. Only one indigenous hardwood species From the results obtained from this test, it reacted positively to the test for the presence is clear that the ethanol extract fluorescence of aluminium. Specimens of Platylophus tri is particularly useful for identification pur foliatus developed a bright blue reaction after poses. As in the case of the water extract, it application of the chrome azurol-s solution is a simple and rapid test. Extracts with char to the freshly exposed end grain. acteristic fluorescence colours could be used This test proved very useful in the identi as important clues during the identification fication of P/aty/ophus trifoliatus, an indig of difficult specimens. enous species which was widely used for Ethano/ extract c%ur household furniture, panelling, framing and The colours of the ethanol extracts of the joinery in the past. As a result of the over- Table 5. Species which show significant differences in the colours of their water and ethanol extracts. Species Family Water extract Ethanol extract Acacia caffra Mimosaceae yellow reddish-brown Ficus burkei Moraceae yellowish-brown colourless Swartzia madagascariensis Caesalpiniaceae yellow red Pterocarpus dalbergioides Fabaceae yellowish-brown colourless Androstachys johnsonii Euphorbiaceae colourless (milky) yellowish-brown Macaranga capensis Euphorbiaceae brown yellow Maytenus peduncularis Celastraceae yellowish-brown colourless Berchemia discolor Rhamnaceae red yellowish-brown Ziziphus mucronata Rhamnaceae orange yellow Adansonia digitata Bombacaceae yellow grey Kigge/aria africana Flacourtiaceae red yellowish-brown Cassipourea ge"ardii Rhizophoraceae reddish-brown yellow Combretum hereroense Combretaceae yellowish-brown red Combretum imberbe Combretaceae red brown Cussonia spicata Araliaceae yellowish-brown colourless Bequertiodendron magalis = Sapotaceae reddish-brown yellow montanum Mimusops caffra Sapotaceae red yellowish-brown Strychnos madagascariensis Loganiaceae brown colourless Brachylaena huillensis Asteraceae yellow reddish-brown Downloaded from Brill.com09/23/2021 12:06:09PM via free access Dyer - Fluorescence of South African woods 87 exploitation of this tirnber species, it has be it is suggested that a form of standardisation come very scarce and items manufactured in this regard be incorporated. This also ap from it are quite valuable today and sought plies to the colour reactions of the water and after by collectors. Positive macroscopic ethanol extracts. identification of the wood of P. trifoliatus is not easy because of its similarity to the exot Acknowledgements ic species Liquidambar styraciflua and Lirio The author expresses her appreciation 10 dendron tulipifera. Only a microscopic com the Directorate of Forestry, Department of parison of the three species makes separation Environment Affairs, South Africa, for fman possible. Platylophus trifoliatus tests positive cial assistance. I am indebted to Dr. Regis ß. with chrome azurol-s, whereas the other two Miller for his valuable assistance and advice. test negative. This feature is therefore useful My sincere thanks also go to R. Grove and for an easy separation of these species. C. Dyer. Kukachka and Miller (1980) noted that the number of positive testing farnilies and References genera is small. The results obtained by this Kukachka, ß.F. & R.B. Miller. 1980. A test correspond with their findings, even chemical spot-test for Aluminum and its though additional families and genera were value in wood identification. IAWA Bull. tested, in this study. n.s. 1: 104-109. Miller, R.ß. 1981. Explanation of coding Conc1usions procedure. IAWA Bull. n.s. 2: 111-145. In conclusion it can be stated that fluores - & P. Baas (coord.) 1981. Standard list of cence has proved to be a valid and useful charaeters suitable for computerized hard character in heartwood identification. The wood identification. Intemational Asso determination of the reactions of wood spe ciation of Wood Anatomists, Rijksherba eies and their extracts to longwave ultravio rium, P.O. Box 9514, 2300 RA Leiden, let light is a rapid and easy test of whieh the The Netherlands (also published in IAW A results are important for the verifieation of BuH. n.s. 2: 99-145). identifieations. Panshin, A.J. & C. de Zeeuw. 1980. Text On a family level the results found in this book of wood technology. 4th Ed. investigation eorrespond to those of previous McGraw-HiH, New York. research, although many of the indigenous Radley, J.A. & J. Grant. 1948. Fluorescence families tested have not yet been studied un analysis in ultra-violet light.3rdEd. Chap der ultraviolet light. man & Hall, London. It is important that a number of specimens Vodrii.zka, 0.1929. Das Mikroskopieren von be tested in all eases as conclusions eannot Holz in filtriertem Ultraviolet-licht. Bota be based on the results found within a single nisches Institut der Hochschule für Boden representative of a speeies. For future studies kultur, Brunn, Czechoslovakia. Downloaded from Brill.com09/23/2021 12:06:09PM via free access