IAWA Bulletin n.s., Vol. 9 (3), 1988: 275-284

ANATOMICAL COMPARISON BETWEEN COMPRESSION WOOD AND OPPOSITE WOOD IN A BRANCH OF KOREAN PINE (PINUS KORAIENSIS)

by

Phil Woo Lee and Young Geun Eom Department of Forest Products, College of Agriculture, Seoul National University, Suwon 440-744, Korea

Summary Compression wood and opposite wood 1978, 1986). Most of its anatomical features formed in the branch of Korean pine (Pinus have been thoroughly investigated by many koraiensis S. et Z.) is described and com­ researchers since long. Despite coexistence pared in qualitative and quantitative anatomi­ of opposite wood with compression wood, cal aspects. however, less studies have been concentrated The qualitative features of compression on the opposite wood or comparison of this wood appeared to differ from those of oppo­ opposite wood with compression wood. site wood in tracheid transition from early­ In earlier studies many anatomical differ­ wood to latewood, growth ring width, late­ ences were found between compression .wood proportion, tracheid shape in cross and wood and opposite wood (TimellI973, 1986; radial section, intercellular spaces, traumatic Park et al. 1979, 1980; Yoshizawa et al. resin canals, helical cavities, distribution of 1981; Lee & Eom 1984; Eom & Lee 1985) vertical epithelium, shape of fusiform rays and normal coniferous wood was considered and cross field pits. In quantitative features as an intermediate between opposite wood there are differences between these two tis­ and compression wood (TimellI973). sues in length and wall thickness of tra­ This paper offers an anatomical compari­ cheids, in number of vertical and horizontal son between compression wood and opposite resin canals (fusiform rays), in width and wood in the branch of Korean pine (Pinus height of fusiform rays, in number and height koraiensis S. et Z.), a species hitherto not of uniseriate rays and in the number of bi­ studied in this respect. seriate rays. Key words: Korean pine (Pinus koraiensis Materials and Methods S. et Z.), branch wood, opposite wood, The compression wood and opposite wood compression wood, anatomical features. Fig. 1) were obtained from a branch of Ko­ rean pine (Pinus koraiensis) on the campus Introduction of the College of Agriculture, Seoul National As a rule, the inclined stems and branches University, Suwon, Korea, and their subdi­ of gymnosperms simultaneously form well­ vided blocks of c. 1 cm3 size were imme­ developed compression wood on the lower diately softened in water in an autoc1ave for part and suppressed opposite wood on the 90 minutes. From these blocks, cross, radial upper part, and this radial growth eccentricity and tangential sections of 20 J.IlIl thickness may be the result of auxin redistribution were cut with a sliding microtome and per­ caused by the action of gravity (Yamaguchi manent slides were prepared following gen­ et al. 1983). erallaboratory techniques (Japan Wood Re­ Compression wood is distinguished easily search Society 1985). by its darker colour from surrounding tissues In the quantitative analysis of each tissue and occurs in Ginkgoales, Coniferales, and the lengths of 100 randornly selected tra­ Taxales among the gymnosperms (Timell cheids were measured from macerations ob-

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became more gradual in wider rings. A grad­ ual transition in compression wood and ab­ rupt transition in opposite wood were also indicated in our previous studies (Lee & Eom 1984; ßom & Lee 1985). The growth ring widths are in the range of 0.9 to 5.1 mm in compression wood and 0.3 to 2.1 mm in opposite wood, which means that the ring width in compression wood is wider than in opposite wood and that in both ring width is very variable. Opposite wood shows great variation in the proportion of latewood. Some growth rings consist almost exclusively of earlywood. Latewood propor­ tion may also vary within a ring. In compres­ sion wood a more or less constant larger late­ 12mrn wood proportion is observed. Jaccard (1919) - indicated considerable variation of growth ring width in opposite wood and TimeIl Fig. 1. Compression wood (CW) and oppo­ (1973) reported that these ring widths in op­ site wood (OW) in the branch of Korean pine posite wood varied greatly with wide rings (Pinus koraiensis S. et Z.). containing a much higher proportion of latewood than the narrow ones, contrary to Mork's observation (1928) that the narrow increments had a higher proportion of late­ tained with Schultze's solution (Berlyn & wood than the wider ones. Core et al. (1961) Miksche 1976) by the aid of an optical bench reported instances where the complete width comparator and wall thickness was measured of the ring in compression wood was made from five cross sectional micrographs. The up of thick-walled, rounded tracheids caus­ numbers ofvertical resin canals were counted ing the ring to appear to be made up entirely in cross surfaces of 4 1t mm', and horizontal of latewood. Park (1983) also suggested that resin canals (fusiform rays) and biseriate rays growth ring width and latewood proportion in tangential surfaces of 4 1t mm', based on decreased continuously at a relatively steep 10 randomly selected parts. The numbers of rate from the compression wood side to the uniseriate rays per mm' were counted in 20 opposite side. randomly selected parts of tangential surfaces The shape of compression wood tracheids, in permanent slides. The height and widths when viewed in cross seetion, is round with of 50 randomly selected fusiform rays and the exception of the vicinity of growth ring the heights of 100 randomly selected uniseri­ boundary (Fig. 4) as reported by Cöte et al. ate rays were also measured. (1967) and Yoshizawa et al. (1982), but op­ posite wood tracheids show more or less Results and Discussion square and rectangular shapes in earlywood The transition from earlywood to late­ and latewood respectiveIy (Fig. 5). In the wood is very gradual in compression wood comparison of opposite, normal, and com­ but abrupt, though wide rings generally show pression wood by TimeIl (1973, 1986), the a more gradual transition than narrow ones, outline of tracheids was reported as square or in opposite wood (Figs. 2 & 3) and the de­ rectangular in opposite wood, angular in nor­ marcation between earlywood and latewood mal wood, and round in compression wood. is more difficult in compression wood. This Intercellular spaces are present in com­ is in agreement with TimeIl (1973, 1986) pression wood with the exception of the vi­ who reported that the transition in opposite cinity of the growth ring boundary (Fig. 4); wood was abrupt in narrow increments but they are absent in opposite wood. This phe-

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nomenon is related to the shape of tracheids and believed to be caused by sliding or intru­ in cross section. Intercellular spaces are sive growth (TimeIl 1981). Recently Yoshi­ known to be present frequently in compres­ zawaet al. (1985) indicated that flattened and sion wood of Larix, Picea, Pinus, and Pseu­ L-shaped tips of tracheids increased in num­ dotsuga (TimellI981, 1986). ber with the development of compression Normal vertical and horizontal resin canals wood due to disturbed intrusive growth be­ are present both in earlywood and latewood tween adjacent cells. of compression wood and opposite wood, As indicated by us (Lee & Eom 1984; buttraumatic vertical resin canals are observ­ Eom & Lee 1985), the cross field pits in the ed only in compression wood (Fig. 6). The earlywood of compression wood show nar­ vertical epithelia in compression wood are ar­ rower and steeper apertures than in opposite ranged in vasicentric, aliform, and confluent wood because of the border on the tracheid forms (Fig. 7) while the opposite wood only side (Figs. 10 & 11). Onaka (1949) reported shows the vasicentric type in analogy with that the simple pits connecting the ray paren­ the classification ofaxial parenchyma in hard­ chyma cells in compression wood were the woods (lAWA Committee 1964). Tylosoids same in all species, and thus could not be arisen through the proliferation of thin-walled used as diagnostic guide in the same way as epithelial cells arecommonly detected in these for normal wood. resin canals of compression wood and oppo­ Inconspicuous nodular end walls and in­ site wood. TimeIl (1973) observed normal dentures in ray parenchyma cells, trabeculae, resin canals both in the earlywood and late­ and strand tracheids around vertical resin wood of opposite wood. Traumatic resin canals were found both in compression wood canals in compression wood were observed and opposite wood of Korean pine (Figs. in some species by Core et al. (1961) and 8, 10, 12, 13) as identified in normal wood these authors concluded that they are not a by us (Lee & Eom 1987). Yumoto and Ohta­ constant feature of compression wood. Sato ni (1981) indicated the presence of spiral and Ishida (1983) in comparing vertical resin grooves in the trabeculae of compression canals in compression wood and normal wood and concluded that these trabeculae wood noted a smaller number of vertical were composed of the same cell walllayers resin canals, more frequent occurrence of as those of host cells. narrow vertical canals, more frequent absence In quantitative features, tracheid lengths ofaxial parenchyma cells, a lower propor­ are 480 to 2,100 Ilm (average 1,220 11m) in tion of thin-walled axial epithelial cells, and compression wood and 520 to 2,500 11m a higher proportion of irregularly shaped (average 1,440 llm) in opposite wood, and axial epithelial cells in compression wood. thus tracheids of compression wood are Helical cavities are observed only in com­ shorter than those of opposite wood. Shel­ pression wood both in earlywood and late­ boume and Ritchie (1968) indicated that tra­ wood (Fig. 8). TimeIl (1978) suggested that cheid length of normal wood was greater than these cavities developed into checks of schi­ that of compression wood with an inverse re­ zogenous origin which were probably forrned lationship with compression wood intensity on drying and sometimes associated with pit and TimeIl (1973) reported that the tracheids openings. Wardrop and Davies (1964), Cöte were relatively long in opposite wood, short et al. (1968), and Timell (1979, 1986) gave in compression wood, and interrnediate in some attention to the origin of helical cavities, normal wood. Park (1984), also, found that perhaps the most conspicuous feature of the length of latewood tracheids increased compression wood, but this problem has not slightly from the compression side toward the been resolved as yet. Occasionally distorted lateral side but decreased thereafter to the op­ tracheid tips occur in compression wood (Fig. posite side in peripheral positions. The wall 9); they were not found in opposite wood. thicknesses of tracheids are 3.5 to 5.3 11m This tracheid distortion was indicated as a (average 4.2 11m) in compression wood and feature of compression wood by Onaka (1949) and Wardrop and Dadswell (1952) (text continued on page 282)

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1;::;: :::=: :::;:~::: ; ~::::::: ::.::: o~ :::: ::;:::::::::: :;:;: :::':: :::: 0 :::: :::: :: ;.: ,: .: . ~ ;:.: : ! ;1! : ~ ~ '::',: :;:: .::;! : ~ ~ :.: ~ :: : ;:: ; =: ;!l: :::: ;" : : : : : ::. :.':. : .::.~ .:.: ~:. ~ :: :':'': -: ~ : .. ::,. :. ".::. : :.: ..: .. , :.;.:., .. ~ .. : • • ' .. • • •: ..... • ' '" ••••...... , .. • '. .. ' ••••' .. 0 -, •'. • •. •.. •.. '... .11 • • ,'••...... ••• ...... -.. ".'.' ...... 1..."" " .. . ·• ..':: ••• "" .' ....'.. -. • • •• - ••• ' .:'".. . '...... oll ... ' .'.; ' I •• • '. I . • • • • ...... • ...... ' ...... : , .. -;., ...... '.... ,:: ..... ~ ., ,' ...... ' .. ' • ••• : •• :. • ' . ' : • • ~ •••• ; : • : : •• , : . : ...... : • • :' •• ...... ' •• I •••• •••••• • ' ..: • ' . ,. • ... .. '1.".: ".. :...... :... ' ,... . ~• ''"··I .. :... ,...... ·': ...'.' ::....••• II.~ , •.••••••••• ••. : ••••. ••• : ..'...... : : .: •• :.:.. ··: ••····' :ii:· ··'·••.•\.··••.\:l · .. p · . :...· ·~:· o ••· ••· · ··" · ...... :. \\!", ...... " .. : ••. : ....••...... : ...... , •• .' "•.• ."• :." : .: ... ; " ~ ...... : ~.;.: : , .. ..• • : "." • ... - , • :.:. .... ::::.'. .., •• :: ••• , . t . \ • .. • ...... '... Fig. 6. Traumatic vertical resin canals in a cross section of compression wood. - Fig. 7. Vasi­ centric, aliform, and confluent (from left to right) vertical epithelium in cross section of com­ pression wood.

Fig. 2. Cross section of compression wood showing a very gradual transition from earlywood to latewood. - Fig. 3. Cross section of opposite wood showing abrupt transition from earlywood to latewood. - Fig. 4. Cross section of compression wood showing rounded tracheids and intercellular spaces (arrowheads) with the exception of the vicinity of the growth ring bound­ ary. - Fig. 5. Cross section of opposite wood showing some square and rectangular tracheids in earlywood and latewood, respectively.

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Fig. 8. Radial seetion of compression wood showing trabeculae (arrowhead) and helical cavi­ ries (arrow) both in earlywood (EW) and latewood (LW). - Fig. 9. Distorted tips of tracheids in radial seetion of compression wood. - Fig. 10. Cross field pits and inconspicuous nodular end walls (arrowhead) of ray parenchyma cell in radial seetion of compression wood.

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Fig. 11. Cross field pits in radial section of opposite wood. - Fig. 12. Trabeculae (arrowhead) in cross section of opposite wood. - Fig. 13. Strand tracheids (arrowhead) in radial section of compression wood. - Fig. 14. Tangential section of compression wood showing rugged fusi­ form ray (arrowhead). - Fig. 15. Fusiform ray in tangential section of opposite wood.

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1.9 to 3.0 11m (average 2.4 11m) in opposite wood and Kennedy (1970) indicated that wood. Panshin and De Zeeuw (1980) record­ compression wood had a much greater pro­ ed that wall thickness of compression wood portion of narrow rays, in part biseriate, than tracheids was approximately twice that of normal wood. TimeH (1972) suggested that comparable normal tracheids. Park (1986) re­ the larger number and size of the rays as oc­ ported that wall thickness of latewood tra­ casionally observed in compression wood, is cheids decreased towards the opposite side associated with rapid growth characteristics from the compression side but such a de­ of this wood. Also, Kramer and Kozlowski crease could not be demonstrated in early­ (1979) noted that the anatomy of ray cells wood. was essentially the same in normal wood and The numbers of vertical resin canals con­ compression wood though sometimes a high­ tained in cross surfaces of 4 1t mm' are 12 to er frequency and larger size of ray cells oc­ 16 (average 14) in compression wood and 18 cur in compression wood, reflecting a higher to 30 (average 23) in opposite wood, thus overall rate of growth. agreeing with the observation by Onaka (1949) that they are fewer in compression wood than in opposite wood. The numbers Conclusion of horizontal resin canals (fusiform rays) Distinct anatomical differences between contained in tangential surfaces of 4 1t mm" compression wood and opposite wood which however, are 22 to 29 (average 24) in com­ formed in the branch of Korean pine (Pinus pression wood and 8 to 12 (average 10) in koraiensis) occurred both in the qualitative opposite wood, which means that horizontal and quantitative features. resin canals (fusiform rays) in compression In the qualitative features, the tracheid tran­ wood are more numerous than in opposite sition from earlywood to latewood in com­ wood. pression wood was even more gradual than The widths and heights of fusiform rays in opposite wood, which made demarcation are 50 to 100 11m (average 69 11m) and 140 to between earlywood and latewood in opposite 340 11m (average 238 11m) in compression wood easier than in compression wood. woodrespectively, and their respective widths Though considerable variation of growth ring and heights inopposite wood are 35 to 60 11m width was observed both in compression (average 47 11m) and 120 to 360 11m (average wood and opposite wood, the compression 266 11m). Thus, fusiform rays in compres­ wood showed wider ring width than opposite sion wood are wider and lower than in oppo­ wood because of growth eccentricity. The site wood. Furthermore, fusiform rays in opposite wood revealed a great variation in compression wood show rugged shapes dif­ Iatewood proportion among the rings and ferently from those in opposite wood (Figs. within a ring as weH, but a more or Iess con­ 14 & 15). The numbers of uniseriate rays per stant and very Iarge Iatewood proportion was mm' in tangential surfaces are 35 to 52 (av­ noted in compression wood. Therefore the erage 44) in compression wood and 31 to 42 compiete width of the ring in compression (average 32) in opposite wood and their wood seemed to consist entirely of latewood, heights are 20 to 300 11m (average 146 11m) in while the ring in opposite wood appeared to compression wood and 30 to 180 11m (aver­ be made up mostly of earlywood. When age 108 11m) in opposite wood, and thus the viewed in cross section, the shape of tra­ uniseriate rays in compression wood are cheids was generally round in compression more numerous and higher than in opposite wood as contras ted with ·the square and rec­ wood. Also, the numbers of biseriate rays tangular shape in earIywood and Iatewood contained in tangential surfaces of 4 1t mm' respectively of opposite wood. Intercellular are 12 to 21 (average 15) in compression spaces, traumatic vertical resin canals, dis­ wood but their detection is very difficuIt in torted tracheids, and helical cavities were opposite wood. Verrall (1928) reported that observed only in compression wood. The the rays were slightly but consistently more vertical epithelia around resin canals in com­ frequent in compression wood than in normal pression wood were arranged in vasicentric,

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aliform, and confluent forms, whereas the Eom, Y.G. & P.W. Lee. 1985. Scanning opposite wood showed only vasicentric epi­ electron microscopic studies on the fea­ thelium. The cross field pits in compression tures of compression wood, opposite wood seem unsuitable for diagnostic pur­ wood, and side wood in branch of pitch poses due to severe morphological alteration, pine (Pinus rigida Miller). Kor.Wood Sci. but the pits in opposite wood appeared to be & Tech. 13: 3-18. useful as an identification criterion because of IAWA Committee on Nomenc1ature. 1964. only a very slight deviation from the fenestri­ Multilingual glossary of terms used in form type, typical of normal wood. wood anatomy. Konkordia, Winterthur. In quantitative features, on the other hand, Jaccard, P. 1919. Nouvelles recherches sur compression wood tracheids showed shorter l'accroissement en epaisseur des arbres. lengths and thicker walls than opposite Fondation Schnydervon Wartensee a Zü• wood. The vertical resin canals were fewer in rich, Librairie Payot et Companie, Lau­ compression wood than in opposite wood, sanne, Geneve. whereas horizontal resin canals (fusiform Japan Wood Research Society. 1985. Wood rays) were more numerous in compression science laboratory book. I. Physics and wood than in opposite wood. The fusiform engineering. Chugai Sangyo Chosakai. rays in compression wood were wider but Kennedy, R.W. 1970. An outlook for basic lower than in opposite wood and had rugged wood anatomy research. Wood and Fiber shapes. The uniseriate rays in compression Sci. 2: 182-187. wood were more numerous and taller than in Kramer, P.J. & T.T. Kozlowski. 1979. opposite wood. Frequently occurring biseri­ Physiology of woody plants. Acad. Press, ate rays also appeared typical of compression !nc., London, New York . .wood. Lee, P.W. & Y.G. Eom. 1984. Scanning electron rnicroscopical study on the com­ pression wood and opposite wood formed Acknowledgements in branch of Juniperus virginiana L. Kor. The authors are grateful to Dr. T. E. TimelI, Wood Sci. & Tech. 12: 47-52. State University of New York, College of - & - 1987. Wood identification of the Environmental Science and Forestry, Syra­ veneer species that grow in Korea. ll. cuse, New York, U.S.A. for reviewing this Wood characteristics and identification paper and making kind and valuable com­ by the microscopic features. Kor. Wood ments. Sci. & Tech. 15: 22-55. Mork, E. 1928. Om tennar. (On compression References wood.) Tidskr. Skogbruk 36: 1-4l. Berlyn, G.P. & lP. Miksche. 1976. Botani­ Onaka, F. 1949. Studies on compression cal rnicrotechnique and cytochernistry. wood and tension wood. Mokuzai Ken­ 1st Ed. The Iowa State Univ. Press, Iowa. kyo No. 1, Wood Res. Inst., Kyoto Uni­ Core, H. A., W. A. CoteJr & A. C Day. 1961. versity. Characteristics of compression wood in Panshin, A.J. & C. de Zeeuw. 1980. Text­ some native conifers. For. Prod. 1. 11: book of wood technology. 4th Ed. 356-362. McGraw-Hill, New York. Cote Jr, W. A., A. C. Day, N. P. Kutscha & Park, S. J. 1983. Structure of 'opposite' T.E. Time1!. 1967. Studies on compres­ wood. I. Structure of the annual ring in sion wood. V. Nature of compression the 'opposite' wood of a horizontal grow­ wood formed in the early springwood of ing stern of Akamatsu (Pinus densiflora conifers. Holzforschung 21: 180-186. S. et Z.). Mokuzai Gakkaishi29: 295- 30l. - ,N.P. Kutscha & T.E. Timel!.1968. Stud­ - 1984. Ibid. III. Variability of the rnicro­ ies on compression wood. VIII. For­ fibril angle and length of the tracheids in mation of cavities in compression wood peripheral positions within each annual tracheids of Abies balsamea (L.) Mil!. ring incIuding the 'opposite' wood. Mo­ Holzforschung 22: 138-144. kuzai Gakkaishi 30: 435-439.

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- 1986. Ibid. V. Structure of 'opposite' - 1986. Compression wood in Gymno­ wood in an inclined stern of Akamatsu sperms. Vol. 1-3. Springer, Berlin, Hei­ (Pinus densiftora S. et Z.). Mokuzai Gak­ deiberg, New York, Tokyo. kaishi 32: 1-5. Verrall, A.F. 1928. A comparative study of - , H. Saiki & H. Harada. 1979. Structure of the structure and physical propenies of branch wood in Akamatsu (Pinus den­ compression wood and normal wood. siftora S. et Z.). I. Distribution of com­ M.S. Thesis. Univ. of Minnesota, St. pression wood, structure of annual ring Paul. and tracheid dimensions. Mokuzai Gak­ Wardrop, A.B. & H.E. Dadswell. 1952. The kaishi 25: 311-317. nature of reaction wood. III. Cell division - , - & - 1980. Ibid. 11. Wall structure of and cell wall formation in conifer sterns. branch wood tracheids. Mem. Coll. Agr. Aust. J. Sci. Res. B-5: 385-398. Kyoto Univ. 115: 33-44. - & G.W. Davies. 1964. The nature of re­ Sato, K. & S. Ishida. 1983. Resin canals in action wood. VIII. The structure and dif­ the wood of Larix leptolepis Gord. III. ferentiation of compression wood. Aust. Morphology of vertical resin canals in J. Bot. 12: 24-38. compression wood. Res. Bull. Coll. Exp. Yamaguchi, K., K. Shimaji & T. Itoh. 1983. For. Hokkaido Univ. 40: 455-462. Simultaneous inhibition and induction of Shelbourne, C.J.A. & K.S. Ritchie. 1968. compression wood formation by morph­ Relationship between degree of compres­ actin in artificially inclined sterns of Japa­ sion wood development and specific grav­ nese larch (Larix leptolepis Gordon). ity and tracheid characteristics in loblolly Wood Sci. & Tech. 17: 81-89. pine (Pinus taeda L.). Holzforschung 22: Yoshizawa, N., T. Itoh & K. Shimaji. 1982. 185-190. Variation in features of compression wood Timell, T.E. 1972. Beobachtungen an Holz­ among gyrnnosperms. Bull. Utsunomiya strahlen im Drukholz. Holz als Roh- und Univ. For. 18: 45-64. Werkstoff 30: 267-273. - , S. Matsumoto & T. Idei. 1985. Morpho­ - 1973. Studies on opposite wood in coni­ logical features of tracheid tips associated fers. II. Histology and ultrastructure. with compression wood formation in Wood Sci. & Tech. 7: 79-91. Larix leptolepis Gord. IAWA Bull. n. s. 6: - 1978. Ultrastructure of compression 245-253. wood in Ginkgo biloba. Wood Sci. & - , I. Toshinaga & K. Okamoto. 1981. Tech. 12: 89-103. Structure of inclined grown Japanese - 1979. Formation of compression wood in black pine (Pinus thunbergii Parl.). I. Dis­ balsam fir. 11. Ultrastructure of the differ­ tribution of compression wood and cell entiating xylem. Holzforschung 33: wall structure of tracheids. Bull. Utsuno­ 181-191. miya Univ. For. 17: 89-105. - 1981. Recent progress in the chemistry, Yumoto, M. & J. Ohtani. 1981. Trabeculae ultrastructure, and formation of compres­ in compression wood tracheids. Proc. sion wood. Int. Symp. on Wood and Pulp­ Hokkaido Br. Japan Wood Res. Soc. 13: ing Chemistry, Stockholm, 1981. SPCI 9-12. Rep. 38, vol. 1: 99-147.

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